Simulating Electron Cloud Effects in Heavy-Ion Beams (open access)

Simulating Electron Cloud Effects in Heavy-Ion Beams

None
Date: June 4, 2004
Creator: Cohen, R; Friedman, A; Lund, S; Molvik, A; Azevedo, T; Vay, J et al.
System: The UNT Digital Library
Mid infrared observations of Van Maanen 2: no substellar companion. (open access)

Mid infrared observations of Van Maanen 2: no substellar companion.

The results of a comprehensive infrared imaging search for the putative 0.06 M{sub {circle_dot}} astrometric companion to the 4.4 pc white dwarf van Mannen 2 are reported. Adaptive optics images acquired at 3.8 {micro}m reveal a diffraction limited core of 0.09 inch and no direct evidence of a secondary. Models predict that at 5 Gyr, a 50 M{sub J} brown dwarf would be only 1 magnitude fainter than van Maanen 2 at this wavelength and the astrometric analysis suggested a separation of 0.2 inch. In the case of a chance alignment along the line of sight, a 0.4 mag excess should be measured. An independent photometric observation at the same wavelength reveals no excess. In addition, there exist published ISO observations of van Maanen 2 at 6.8 {micro}m and 15.0 {micro}m which are consistent with photospheric flux of a 6750 K white dwarf. If recent brown dwarf models are correct, there is no substellar companion with T{sub eff} {approx}> 500 K.
Date: November 3, 2004
Creator: Farihi, J; Becklin, E & Macintosh, B
System: The UNT Digital Library
Redesign of the CKM RICH velocity spectrometers for use in a 1/4 GHz un separated beam (open access)

Redesign of the CKM RICH velocity spectrometers for use in a 1/4 GHz un separated beam

I report here a redesign of the CKM RICH velocity spectrometers for use in a 1/4 GHz unseparated beam adapted to the KTeV beam line and detector hall at Fermilab (P940). The redesigns reported here comprise modest modification to the original designs for CKM(E921) to accommodate the change in beam flux, momentum, and momentum bite of the primary beam. The ultimate performance of the velocity spectrometer systems, as quantified by the missing mass squared resolution for K{sup +} {yields} {pi}{sup +} x{sup 0}, remains largely unchanged from the original design.
Date: January 1, 2004
Creator: Cooper, Peter S. & Engelfried, Jurgen
System: The UNT Digital Library
Evolution of the Regional Coda Methodology (open access)

Evolution of the Regional Coda Methodology

For the past decade Lawrence Livermore National Laboratory (LLNL) and Los Alamos National Laboratory (LANL), have been developing and testing a stable, regional coda magnitude methodology for the determination of magnitude and yield. The motivation behind this research was to take advantage of the averaging nature of coda waves in support of monitoring small seismic events from a sparse regional seismic network (e.g., International Monitoring System (IMS) network). The methodology as described in Mayeda et al., (2003) has been successfully applied in a variety of tectonic settings where the assumption of a 1-D, radially symmetric path correction was sufficient. In general, this resulted in inter-station amplitude scatter that was 3-to-4 times smaller than the traditional approach using direct S, Lg and surface waves (0.02< f <8.0-Hz). However, in more laterally complex regions there is a need to extend this approach to account for smaller scale 2-D variations in structure, especially at frequencies above {approx}1-Hz. Recently, Phillips et al., (2003) have applied a 2-D approach to data in central Asia by assuming that the coda envelope amplitude could be idealized as if it were a direct wave. They performed a tomography to invert for Q along the path and through the …
Date: July 15, 2004
Creator: Mayeda, K; Philips, W; Malagnini, L & Dreger, D
System: The UNT Digital Library
Transforming the Market for Sustainable Design: Effective Public Policies and Strategies; Preprint (open access)

Transforming the Market for Sustainable Design: Effective Public Policies and Strategies; Preprint

The federal government strives to lead by example in energy and resource management and architectural design. This paper explores how public agencies are supporting that goal by using sustainable practices in the design and operation of their buildings. It presents some elements to consider in establishing a policy for sustainable design and a system for implementing that policy, including some of the most difficult implementation issues agencies have to face. The paper also highlights some of the strengths and weaknesses of federal, state, and local policies and practices governing the design of public buildings; two case studies provide examples. Different approaches are included to help agencies evaluate their effectiveness at various levels of government. And recommendations are made for agencies and others who are committed to sustainable design in both new construction and major renovations.
Date: May 1, 2004
Creator: Carlisle, N.; Glickman, J.; Brown, M.; Foster, M.; Bennett, A. K. & Sandler, K.
System: The UNT Digital Library
X-ray Spectropolarimetry of high temperature and high density plasma supported by LLNL Electron Beam Ion Trap Experiments (open access)

X-ray Spectropolarimetry of high temperature and high density plasma supported by LLNL Electron Beam Ion Trap Experiments

Plasma polarization spectroscopy work done by our group since the 3rd US-Japan PPS Workshop is overviewed. Theoretically, the polarization dependence on various electron distribution functions for He-like, Ne-like, and Ni-like x-ray transitions for a wide range of Z has been investigated. In particular, this study was focused on the polarization dependence for monoenergetic and steep electron distribution functions. The diagnostically important spectral lines and features of K-, L-, and M-shell ions were identified which can be used in x-ray spectropolarimetry of plasma. Importance of polarization-sensitive LLNL Electron Beam Ion Trap data is emphasized. The results of the UNR polarization-sensitive Ti and Mo x-pinch experiments are discussed.
Date: March 15, 2004
Creator: Shlyaptseva, A S; Kantsyrev, V L; Ouart, N D; Fedin, D A; Neill, P; Harris, C et al.
System: The UNT Digital Library
Fs Laser Fabrication of Photonic Structures in Glass: the Role of Glass Composition (open access)

Fs Laser Fabrication of Photonic Structures in Glass: the Role of Glass Composition

The use of fs lasers to directly write photonic structures inside a glass has great potential as a fabrication method for three-dimensional all-optical integrated components. The ability to use this technique with different glass compositions--specifically tailored for a specific photonics application--is critical to its successful exploitation. Consequently, it is important to understand how glass composition effects waveguide fabrication with fs laser pulses and how different glasses are structurally modified after exposure to fs laser pulses. We have used confocal laser spectroscopy to monitor the changes in glass structure that are associated with waveguide fabrication. Using a low power continuous wave (cw) Ar laser as excitation source we have measured both Raman and fluorescence spectra of the modified regions. Raman spectroscopy provides us with information on the network structure, whereas fluorescence measurements reveal the presence of optically active point defects in the glass. In this paper we review our work on fs-laser fabrication and characterization of photonic structures in glass and discuss the effect of glass composition on processing parameters and structural modification.
Date: June 16, 2004
Creator: Krol, D M; Chan, J W; Huser, T R; Risbud, S H & Hayden, J S
System: The UNT Digital Library
Hyperspectral Mineral Mapping in Support of Geothermal Exploration: Examples from Long Valley Caldera, CA and Dixie Valley, NV, USA (open access)

Hyperspectral Mineral Mapping in Support of Geothermal Exploration: Examples from Long Valley Caldera, CA and Dixie Valley, NV, USA

Growing interest and exploration dollars within the geothermal sector have paved the way for increasingly sophisticated suites of geophysical and geochemical tools and methodologies. The efforts to characterize and assess known geothermal fields and find new, previously unknown resources has been aided by the advent of higher spatial resolution airborne geophysics (e.g. aeromagnetics), development of new seismic processing techniques, and the genesis of modern multi-dimensional fluid flow and structural modeling algorithms, just to name a few. One of the newest techniques on the scene, is hyperspectral imaging. Really an optical analytical geochemical tool, hyperspectral imagers (or imaging spectrometers as they are also called), are generally flown at medium to high altitudes aboard mid-sized aircraft and much in the same way more familiar geophysics are flown. The hyperspectral data records a continuous spatial record of the earth's surface, as well as measuring a continuous spectral record of reflected sunlight or emitted thermal radiation. This high fidelity, uninterrupted spatial and spectral record allows for accurate material distribution mapping and quantitative identification at the pixel to sub-pixel level. In volcanic/geothermal regions, this capability translates to synoptic, high spatial resolution, large-area mineral maps generated at time scales conducive to both the faster pace of …
Date: March 3, 2004
Creator: Pickles, W. L.; Martini, B. A.; Silver, E. A. & Cocks, P. A.
System: The UNT Digital Library
Measurement of orbitally excited D-mesons at CDF II (open access)

Measurement of orbitally excited D-mesons at CDF II

Results of the first measurement of {sup 3}P orbitally excited neutral D-meson states, D*{sub 2}{sup 0} and D{sub 1}{sup 0}, produced in hadron collisions at the Tevatron are presented. Using data from the displaced track trigger, CDF II collects a large sample of these states in decay modes D*{sup +} {pi}{sup -}, D{sup +} {pi}{sup -}. Masses and widths of both states have been measured with precision better than or comparable to that of the world average.
Date: December 1, 2004
Creator: Gorelov, Igor V.
System: The UNT Digital Library
Intracavity adaptive correction of a 10 kW, solid-state, heat-capacity laser (open access)

Intracavity adaptive correction of a 10 kW, solid-state, heat-capacity laser

The Solid-State, Heat-Capacity Laser (SSHCL), under development at Lawrence Livermore National Laboratory (LLNL) is a large aperture (100 cm{sup 2}), confocal, unstable resonator requiring near-diffraction-limited beam quality. There are two primary sources of the aberrations in the system: residual, static aberrations from the fabrication of the optical components and predictable, time-dependent, thermally-induced index gradients within the gain medium. A deformable mirror placed within the cavity is used to correct the aberrations that are sensed externally with a Shack-Hartmann wavefront sensor. Although the complexity of intracavity adaptive correction is greater than that of external correction, it enables control of the mode growth within the resonator, resulting in the ability to correct a more aberrated system longer. The overall system design, measurement techniques and correction algorithms are discussed. Experimental results from initial correction of the static aberrations and dynamic correction of the time-dependent aberrations are presented.
Date: May 13, 2004
Creator: LaFortune, K N; Hurd, R L; Brase, J M & Yamamoto, R M
System: The UNT Digital Library
The Evaluated Gamma-Ray Activation File (EGAF) (open access)

The Evaluated Gamma-Ray Activation File (EGAF)

None
Date: September 15, 2004
Creator: Firestone, R. B.; Molnar, G. L.; Revay, Z.; Belgya, T.; McNabb, D. P. & Sleaford, B.
System: The UNT Digital Library
SECONDARY ELECTRON EMISSION MEASUREMENTS FOR TIN COATING ON THE STAINLESS STEEL OF SNS ACCUMULATOR RING VACUUM CHAMBER. (open access)

SECONDARY ELECTRON EMISSION MEASUREMENTS FOR TIN COATING ON THE STAINLESS STEEL OF SNS ACCUMULATOR RING VACUUM CHAMBER.

BNL is responsible for the design and construction of the US Spallation Neutron Source (SNS) accumulator ring. Titanium Nitride (TiN) coating on the stainless steel vacuum chamber of the SNS accumulator ring is needed to reduce the secondary electron yield (SEY) and the undesirable resonant multiplication of electrons. The total SEY of TiN coated stainless steel material has been measured after coating samples were exposed to air and after electron and ion bombardment. We report here about TiN coating system setup at BNL and SEY measurements results at CERN, SLAC and KEK. We also present some simulation results of SNS accumulator ring electron-cloud effects using different SEY values.
Date: July 5, 2004
Creator: HE,P. HSEUH,H. C. TODD,R. J. ET AL.
System: The UNT Digital Library
Experimental Studies of Electron and Gas Sources in a Heavy-Ion Beam (open access)

Experimental Studies of Electron and Gas Sources in a Heavy-Ion Beam

None
Date: October 12, 2004
Creator: Molvik, A W; Cohen, R H; Friedman, A; Covo, M K; Lund, S M; Seidl, P A et al.
System: The UNT Digital Library
Speckle Imaging of Titan at 2 microns: Surface Albedo, Haze Optical Depth, and Tropospheric Clouds 1996-1998 (open access)

Speckle Imaging of Titan at 2 microns: Surface Albedo, Haze Optical Depth, and Tropospheric Clouds 1996-1998

We present results from 14 nights of observations of Titan in 1996-1998 using near-infrared (centered at 2.1 microns) speckle imaging at the 10-meter W.M. Keck Telescope. The observations have a spatial resolution of 0.06 arcseconds. We detect bright clouds on three days in October 1998, with a brightness about 0.5% of the brightness of Titan. Using a 16-stream radiative transfer model (DISORT) to model the central equatorial longitude of each image, we construct a suite of surface albedo models parameterized by the optical depth of Titan's hydrocarbon haze layer. From this we conclude that Titan's equatorial surface albedo has plausible values in the range of 0-0.20. Titan's minimum haze optical depth cannot be constrained from this modeling, but an upper limit of 0.3 at this wavelength range is found. More accurate determination of Titan's surface albedo and haze optical depth, especially at higher latitudes, will require a model that fully considers the 3-dimensional nature of Titan's atmosphere.
Date: February 11, 2004
Creator: Gibbard, S. G.; Gavel, D.; Ghez, A. M.; de Pater, I.; Max, C. E.; Young, E. F. et al.
System: The UNT Digital Library
Adapting high-resolution speckle imaging to moving targets and platforms (open access)

Adapting high-resolution speckle imaging to moving targets and platforms

High-resolution surveillance imaging with apertures greater than a few inches over horizontal or slant paths at optical or infrared wavelengths will typically be limited by atmospheric aberrations. With static targets and static platforms, we have previously demonstrated near-diffraction limited imaging of various targets including personnel and vehicles over horizontal and slant paths ranging from less than a kilometer to many tens of kilometers using adaptations to bispectral speckle imaging techniques. Nominally, these image processing methods require the target to be static with respect to its background during the data acquisition since multiple frames are required. To obtain a sufficient number of frames and also to allow the atmosphere to decorrelate between frames, data acquisition times on the order of one second are needed. Modifications to the original imaging algorithm will be needed to deal with situations where there is relative target to background motion. In this paper, we present an extension of these imaging techniques to accommodate mobile platforms and moving targets.
Date: February 5, 2004
Creator: Carrano, C J & Brase, J M
System: The UNT Digital Library
Flor-Essence? Herbal Tonic Promotes Mammary Tumor Development in Sprague Dawley Rats (open access)

Flor-Essence? Herbal Tonic Promotes Mammary Tumor Development in Sprague Dawley Rats

Background: Women who are diagnosed with breast cancer often self-administer complementary and alternative medicines to augment their conventional treatments, improve health, or prevent recurrence. Flor-Essence{reg_sign} Tonic is a complex mixture of herbal extracts used by cancer patients because of anecdotal evidence that it can treat or prevent disease. Methods: Female Sprague Dawley rats were given water or exposed to 3% or 6% Flor-Essence{reg_sign} beginning at one day of age. Mammary tumors were induced with a single oral 40 mg/kg/bw dose of dimethylbenz(a)anthracene at 50 days of age and sacrificed at 23 weeks. Rats were maintained on AIN-76A diet. Results: Control rats had palpable mammary tumor incidence of 51.0% at 19 weeks of age compared to 65.0% and 59.4% for the 3% and 6% Flor-Essence{reg_sign} groups respectively. Overall, no significant difference in time until first palpable tumor was detected among any of the groups. At necropsy, mammary tumor incidence was 82.5% for controls compared to 90.0% and 97.3% for rats consuming 3% and 6% Flor-Essence{reg_sign}, respectively. Mean mammary tumor multiplicity ({+-}SES) for the controls was 2.8 ({+-} 0.5) and statistically different from the 3% or 6% Flor- Essence{reg_sign} groups with 5.2 ({+-} 0.7), and 4.8 ({+-} 0.6), respectively (p{<=}0.01). As expected, …
Date: January 28, 2004
Creator: Bennett, L; Montgomery, J; Steinberg, S & Kulp, K
System: The UNT Digital Library
RF TECHNIQUES FOR IMPROVED LUMINOSITY IN RHIC. (open access)

RF TECHNIQUES FOR IMPROVED LUMINOSITY IN RHIC.

The luminosity of the Relativistic Heavy Ion Collider has improved significantly [1] over the first three physics runs. A number of special rf techniques have been developed to facilitate higher luminosity. The techniques described herein include: an ultra low-noise rf source for the 197 MHz storage rf system, a frequency shift switch-on technique for transferring bunches from the acceleration to the storage system, synchronizing the rings during the energy ramp (including crossing the transition energy) to avoid incidental collisions, installation of dedicated 200 MHZ cavities to provide longitudinal Landau damping on the ramp, and the development of a bunch merging scheme in the Booster to increase the available bunch intensity from the injectors.
Date: July 5, 2004
Creator: BRENNAN,J. M. BLASKIEWICZ,J. BUTLER,J. DELONG,J. FISCHER,W. HAYES,T.
System: The UNT Digital Library
Boron-Carbide Barrier Layers in Scandium-Silicon Multilayers (open access)

Boron-Carbide Barrier Layers in Scandium-Silicon Multilayers

None
Date: March 25, 2004
Creator: Jankowski, Alan Frederic; Saw, Cheng K.; Walton, Christopher C.; Hayes, Jeffrey P. & Nilsen, Joseph
System: The UNT Digital Library
Generation of Electric and Magnetic Fields During Detonation of High Explosive Charges in Boreholes (open access)

Generation of Electric and Magnetic Fields During Detonation of High Explosive Charges in Boreholes

We present experimental results of a study of electromagnetic field generation during underground detonation of high explosive charges in holes bored in sandy loam and granite. Test conditions and physico-mechanical properties of the soil exert significant influence on the parameters of electromagnetic signals generated by underground TNT charges with masses of 2 - 200 kg. The electric and magnetic field experimental data are satisfactorily described by an electric dipole model with the source embedded in a layered media.
Date: June 4, 2004
Creator: Soloviev, S. & Sweeney, J.
System: The UNT Digital Library
X-Ray Line Measurements with High Efficiency Bragg Crystals (open access)

X-Ray Line Measurements with High Efficiency Bragg Crystals

We have studied the focusing properties of two highly oriented pyrolitic graphite (HOPG) spectrometers, which differ in the degree of the mosaic spread: ZYA with a low mosaic spread ({gamma}=0.4 degrees) and ZYH with a large mosaic spread ({gamma}=3.5 degrees). In order to assess the crystal performance for a variety of different experiments, various K{alpha} and K{beta} x-ray lines have been produced using a high-intensity ({approx}>10{sup 17} W/cm{sup 2}) short-pulse ({approx} 100 fs) laser beam focused onto Ti, V, Zn, and Cu foils. The measured spectral resolution of the HOPG crystals in both first and second order diffraction has been compared with theoretical predictions. Using known values for the peak reflectivity of HOPG crystals, we have also computed K{alpha} x-ray conversion efficiencies of Ti, V, Zn, and Cu. These results are important to estimate the optimal conditions under which different types of HOPG monochromators can be used for the detection of weak x-ray signals as the one encountered in x-ray Thomson/Compton scattering experiments.
Date: April 1, 2004
Creator: Pak, A; Gregori, G; Knight, J; Campbell, K; Landen, O & Glenzer, S
System: The UNT Digital Library
In-Situ TEM Observations of Interface Sliding and Migration in a Refined Lamellar TiAl Alloy (open access)

In-Situ TEM Observations of Interface Sliding and Migration in a Refined Lamellar TiAl Alloy

The stability of lamellar interfaces in lamellar TiAl by straining at ambient temperatures has been investigated using in-situ straining techniques performed in a transmission electron microscope in order to obtain direct evidence to support the previously proposed creep mechanisms in refined lamellar TiAl based upon the interface sliding in association with the cooperative motion of interfacial dislocations. The results have revealed that both sliding and migration of lamellar interfaces can take place as a result of the cooperative motion of interfacial dislocations.
Date: February 18, 2004
Creator: Schwartz, A J; Nieh, T G & Hsiung, L M
System: The UNT Digital Library
Development of Burning Plasma and Advanced Scenarios in the DIII-D Tokamak (open access)

Development of Burning Plasma and Advanced Scenarios in the DIII-D Tokamak

Significant progress in the development of burning plasma scenarios, steady-state scenarios at high fusion performance, and basic tokamak physics has been made by the DIII-D Team. Discharges similar to the ITER baseline scenario have demonstrated normalized fusion performance nearly 50% higher than required for Q = 10 in ITER, under stationary conditions. Discharges that extrapolate to Q {approx} 10 for longer than one hour in ITER at reduced current have also been demonstrated in DIII-D under stationary conditions. Proof of high fusion performance with full noninductive operation has been obtained. Underlying this work are studies validating approaches to confinement extrapolation, disruption avoidance and mitigation, tritium retention, ELM avoidance, and operation above the no-wall pressure limit. In addition, the unique capabilities of the DIII-D facility have advanced studies of the sawtooth instability with unprecedented time and space resolution, threshold behavior in the electron heat transport, and rotation in plasmas in the absence of external torque.
Date: October 18, 2004
Creator: Luce, T C
System: The UNT Digital Library
Position Estimation of Transceivers in Communication Networks (open access)

Position Estimation of Transceivers in Communication Networks

With rapid developments in wireless sensor networks, there is a growing need for transceiver position estimation independent of GPS, which may not be available in indoor networks. Our approach is to use range estimates from time-of-flight (TOF) measurements, a technique well suited to large bandwidth physical links, such as in ultra-wideband (UWB) systems. In our UWB systems, pulse duration less than 200 psecs can easily be resolved to less than a foot. Assuming an encoded UWB physical layer, we first test positioning accuracy using simulations. We are interested in sensitivity to range errors and the required number of ranging nodes, and we show that in a high-precision environment, such as UWB, the optimal number of transmitters is four. Four transmitters with {+-}20ft. range error can locate a receiver to within one or two feet. We then implement these algorithms on an 802.11 wireless network and demonstrate the ability to locate a network access point to approximately 20 feet.
Date: January 20, 2004
Creator: Dowla, F. & Kent, C.
System: The UNT Digital Library
Simultaneous imaging of the near- and far-field intensity distributions of the Ni-like Sn X-ray laser (open access)

Simultaneous imaging of the near- and far-field intensity distributions of the Ni-like Sn X-ray laser

We report on 2D near-field imaging experiments of the 11.9-nm Sn X-ray laser that were performed with a set of novel Mo/Y multilayer mirrors having reflectivities of up to {approx}45% at normal and at 45 incidence. Second-moment analysis of the X-ray laser emission was used to determine values of the X-ray beam propagation factor M{sup 2} for a range of irradiation parameters. The results reveal a reduction of M{sup 2} with increasing prepulse amplitude. The spatial size of the output is a factor of {approx}2 smaller than previously measured for the 14.7-nm Pd X-ray laser, while the distance of the X-ray emission with respect to the target surface remains roughly the same.
Date: July 26, 2004
Creator: Staub, F; Braud, M; Balmer, J E; Nilsen, J & Bajt, S
System: The UNT Digital Library