Real-time Studies of Shocked Polycrystalline Materials with Single-Pulse X-ray Diffraction (open access)

Real-time Studies of Shocked Polycrystalline Materials with Single-Pulse X-ray Diffraction

Characteristic K-α x-rays used for single-pulse XRD are conventionally produced by a 37-stage high-voltage Marx pulse generator coupled to a vacuum needle-and-washer x-ray diode via coaxial transmission line. A large field-of-view x-ray image plate detection system typically enables observation of several Debye-Scherrer rings. Recently, we have developed a fiber-optic reducer, coupled to a CCD camera, to obtain low-noise, large field-of-view images. The direct beam spot is produced by bremsstrahlung radiation attenuated by a twomillimeter tungsten beam stop. Determination of the direct beam position is necessary to perform the ring integration.
Date: May 25, 2011
Creator: Morgan, Dane V.
Object Type: Article
System: The UNT Digital Library
Final Scientific Report (open access)

Final Scientific Report

Hackensack University Medical Center's major initiative to create a cleaner healthier and safer environment for patients, employees and the community served by the medical center is built on its commitment to protect the environment and conserve precious energy resources. Since 2004 the Medical Center launched a long term campaign to temper the negative environmental impact of proposed and existing new construction at the medical center and to improve campus wide overall energy efficiency. The plan was to begin by implementing a number of innovative and eco-friendly enhancements to the Gabrellian Women's and Children's Pavilion, in construction at the time, which would lead to Certification by the US Green Building Councils Leadership & Environmental Design (LEED) program. In addition the medical center would evaluate the feasibility of implementing a photovoltaic system in the new construction (in development and planned) to provide clean pollution free electricity. The steps taken to achieve this included conducting a feasibility study complete with architectural and engineering assessments to determine the potential for implementation of a photovoltaic system on the campus and also to conduct an energy survey that would focus on determining specific opportunities and upgrades that would lead to a healthier energy efficient interior environment …
Date: May 25, 2011
Creator: Lutwick, Suzanne & Cunning, Helen
Object Type: Report
System: The UNT Digital Library
Optimization of Operating Parameters for Minimum Mechanical Specific Energy in Drilling (open access)

Optimization of Operating Parameters for Minimum Mechanical Specific Energy in Drilling

Efficiency in drilling is measured by Mechanical Specific Energy (MSE). MSE is the measure of the amount of energy input required to remove a unit volume of rock, expressed in units of energy input divided by volume removed. It can be expressed mathematically in terms of controllable parameters; Weight on Bit, Torque, Rate of Penetration, and RPM. It is well documented that minimizing MSE by optimizing controllable factors results in maximum Rate of Penetration. Current methods for computing MSE make it possible to minimize MSE in the field only through a trial-and-error process. This work makes it possible to compute the optimum drilling parameters that result in minimum MSE. The parameters that have been traditionally used to compute MSE are interdependent. Mathematical relationships between the parameters were established, and the conventional MSE equation was rewritten in terms of a single parameter, Weight on Bit, establishing a form that can be minimized mathematically. Once the optimum Weight on Bit was determined, the interdependent relationship that Weight on Bit has with Torque and Penetration per Revolution was used to determine optimum values for those parameters for a given drilling situation. The improved method was validated through laboratory experimentation and analysis of published …
Date: May 25, 2011
Creator: Hamrick, Todd
Object Type: Thesis or Dissertation
System: The UNT Digital Library
SPS Ecloud Instabilities - Analysis of Machine Studies and Implications for Ecloud Feedback (open access)

SPS Ecloud Instabilities - Analysis of Machine Studies and Implications for Ecloud Feedback

The SPS at high intensities exhibits transverse single bunch instabilities with signatures consistent with an Ecloud driven instability. We present recent MD data from the SPS, details of the instrument technique and spectral analysis methods which help reveal complex vertical motion that develops within a subset of the injected bunch trains. The beam motion is detected via wideband exponential taper striplines and delta-sigma hybrids. The raw sum and difference data is sampled at 50 GHz with 1.8 GHz bandwidth. Sliding window FFT techniques and RMS motion techniques show the development of large vertical tune shifts on portions of the bunch of nearly 0.025 from the base tune of 0.185. Results are presented via spectrograms and bunch slice trajectories to illustrate development of the unstable beam and time scale of development along the injected bunch train. The study shows that the growing unstable motion occupies a very broad frequency band of 1.2 GHz. These measurements are compared to numerical simulation results, and the system parameter implications for an Ecloud feedback system are outlined.
Date: May 25, 2011
Creator: Fox, J.; Bullitt, A.; Mastorides, T.; Ndabashimiye, G.; Rivetta, C. H.; Turgut, O. et al.
Object Type: Article
System: The UNT Digital Library
Breaking and Moving Hotspots in a Large Grain Nb Cavity with a Laser Beam (open access)

Breaking and Moving Hotspots in a Large Grain Nb Cavity with a Laser Beam

Magnetic vortices pinned near the inner surface of SRF Nb cavities are a possible source of RF hotspots, frequently observed by temperature mapping of the cavities outer surface at RF surface magnetic fields of about 100 mT. Theoretically, we expect that the thermal gradient provided by a 10 W green laser shining on the inner cavity surface at the RF hotspot locations can move pinned vortices to different pinning locations. The experimental apparatus to send the beam onto the inner surface of a photoinjector-type large-grain Nb cavity is described. Preliminary results on the changes in thermal maps observed after applying the laser heating are also reported.
Date: July 25, 2011
Creator: Ciovati, G.; Cheng, G.; Flood, R. J.; Jordan, K.; Kneisel, P.; Morrone, M. L. et al.
Object Type: Article
System: The UNT Digital Library
Finite size effect on spread of resonance frequencies in arrays of coupled vortices (open access)

Finite size effect on spread of resonance frequencies in arrays of coupled vortices

Dynamical properties of magnetic vortices in arrays of magnetostatically coupled ferromagnetic disks are studied by means of a broadband ferromagnetic-resonance (FMR) setup. Magnetic force microscopy and magnetic transmission soft X-ray microscopy are used to image the core polarizations and the chiralities which are both found to be randomly distributed. The resonance frequency of vortex-core motion strongly depends on the magnetostatic coupling between the disks. The parameter describing the relative broadening of the absorption peak observed in the FMR transmission spectra for a given normalized center-to-center distance between the elements is shown to depend on the size of the array.
Date: January 25, 2011
Creator: Vogel, Andreas; Drews, André; Im, Mi-Young; Fischer, Peter & Meier, Guido
Object Type: Article
System: The UNT Digital Library
MCNP5 CALCULATIONS REPLICATING ARH-600 NITRATE DATA (open access)

MCNP5 CALCULATIONS REPLICATING ARH-600 NITRATE DATA

This report serves to extend the previous document: 'MCNP Calculations Replicating ARH-600 Data' by replicating the nitrate curves found in ARH-600. This report includes the MCNP models used, the calculated critical dimension for each analyzed parameter set, and the resulting data libraries for use with the CritView code. As with the ARH-600 data, this report is not meant to replace the analysis of the fissile systems by qualified criticality personnel. The M CNP data is presented without accounting for the statistical uncertainty (although this is typically less than 0.001) or bias and, as such, the application of a reasonable safety margin is required. The data that follows pertains to the uranyl nitrate and plutonium nitrate spheres, infinite cylinders, and infinite slabs of varying isotopic composition, reflector thickness, and molarity. Each of the cases was modeled in MCNP (version 5.1.40), using the ENDF/B-VI cross section set. Given a molarity, isotopic composition, and reflector thickness, the fissile concentration and diameter (or thicknesses in the case of the slab geometries) were varied. The diameter for which k-effective equals 1.00 for a given concentration could then be calculated and graphed. These graphs are included in this report. The pages that follow describe the regions …
Date: October 25, 2011
Creator: Finfrock, S. H.
Object Type: Report
System: The UNT Digital Library
TOF-SIMS Analysis of Hydrogen in Niobium, From 160 deg. K to 475 deg. K (open access)

TOF-SIMS Analysis of Hydrogen in Niobium, From 160 deg. K to 475 deg. K

Niobium (Nb) is the material of choice for superconducting radio frequency (SRF) cavities due to its high critical temperature and critical magnetic field. Interstitial impurity elements such as H directly influence the efficiency of these cavities. Quantification of H in Nb is difficult since H is extremely mobile in Nb with a very high diffusion coefficient even at room temperature. In the presented work, Time of Flight Secondary Ion Mass Spectrometry (TOF-SIMS) was used to characterize H in Nb over a wide temperature range (160°K to 475°K) in situ to check for changes in mobility. Multiple experiments showed that as the specimen temperature is decreased below 300 °K, the H/Nb intensity changes by first increasing and then decreasing drastically at temperatures below 200°K. As specimen temperature is increased from 300°K to 450°K, the H/Nb intensity decreases. Remarkably, the H intensity with respect to Nb increases with time at 475°K (approximately 200°C). Correlation between this data and the H-Nb phase diagram appears to account for the H behaviour.
Date: July 25, 2011
Creator: P. Maheshwari, A.D. Batchelor, D.P. Griffis, F.A. Stevie, C. Zhou, G. Ciovati, R. Myneni, M. Rigsbee
Object Type: Article
System: The UNT Digital Library
Radoptic x-ray detection with picosecond resolution (open access)

Radoptic x-ray detection with picosecond resolution

None
Date: July 25, 2011
Creator: Lowry, M. E.; Vernon, S. P.; Steele, P. T.; Bennett, C. V.; Hernandez, V. J.; Moran, B. et al.
Object Type: Article
System: The UNT Digital Library
Nuclear Nonproliferation and Arms Control Primer Prepared for the Blue Ribbon Commission on America’s Nuclear Future (open access)

Nuclear Nonproliferation and Arms Control Primer Prepared for the Blue Ribbon Commission on America’s Nuclear Future

To provide a brief overview of key arms control and nonproliferation arrangements for the layperson that may be relevant to the Commission's comprehensive review of policies for managing the back end of the nuclear fuel cycle. Primer would be published by the Commission and made publicly available, probably as an appendix to a larger Commission report.
Date: May 25, 2011
Creator: Williams, Laura S.
Object Type: Report
System: The UNT Digital Library
EVALUATION OF ALTERNATIVE STRONIUM AND TRANSURANIC SEPARATION PROCESSES (open access)

EVALUATION OF ALTERNATIVE STRONIUM AND TRANSURANIC SEPARATION PROCESSES

In order to meet contract requirements on the concentrations of strontium-90 and transuranic isotopes in the immobilized low-activity waste, strontium-90 and transuranics must be removed from the supernate of tanks 241-AN-102 and 241-AN-107. The process currently proposed for this application is an in-tank precipitation process using strontium nitrate and sodium permanganate. Development work on the process has not proceeded since 2005. The purpose of the evaluation is to identify whether any promising alternative processes have been developed since this issue was last examined, evaluate the alternatives and the baseline process, and recommend which process should be carried forward.
Date: April 25, 2011
Creator: CS, SMALLEY
Object Type: Report
System: The UNT Digital Library
Study of Windows Effects for Shock Wave Temperature Measurements (open access)

Study of Windows Effects for Shock Wave Temperature Measurements

Temperature measurements of shocked plutonium are needed for improved understanding of its equation of state (EOS) and will enable better understanding and reliability of the U.S. nuclear weapon stockpile.
Date: May 25, 2011
Creator: W. D. Turley, G. Stevens, L. Veeser, D. Holtkamp, A. Seifter
Object Type: Article
System: The UNT Digital Library
Embodied Energy and Off-Grid Lighting (open access)

Embodied Energy and Off-Grid Lighting

The greenhouse gas (GHG) emissions from fuel-based lighting are substantial given the paltry levels of lighting service provided to users, leading to a great opportunity for GHG mitigation byencouraging the switch from fuel-based to rechargeable LED lighting. However, as with most new energy technology, switching to efficient lighting requires an up-front investment of energy(and GHGs) embedded in the manufacture of replacement components. We studied a population of off-grid lighting users in 2008-2009 in Kenya who were given the opportunity to adopt LEDlighting. Based on their use patterns with the LED lights and the levels of kerosene offset we observed, we found that the embodied energy of the LED lamp was"paid for" in only one month for grid charged products and two months for solar charged products. Furthermore, the energyreturn-on investment-ratio (energy produced or offset over the product's service life divided by energy embedded) for off-grid LED lighting ranges from 12 to 24, which is on par with on-gridsolar and large-scale wind energy. We also found that the energy embodied in the manufacture of a typical hurricane lantern is about one-half to one-sixth of that embodied in the particular LEDlights that we evaluated, indicating that the energy payback time would be …
Date: January 25, 2011
Creator: Alstone, Peter; Mills, Evan & Jacobson, Arne
Object Type: Report
System: The UNT Digital Library
Economic Impacts of Wind Turbine Development in U.S. Counties (open access)

Economic Impacts of Wind Turbine Development in U.S. Counties

The objective is to address the research question using post-project construction, county-level data, and econometric evaluation methods. Wind energy is expanding rapidly in the United States: Over the last 4 years, wind power has contributed approximately 35 percent of all new electric power capacity. Wind power plants are often developed in rural areas where local economic development impacts from the installation are projected, including land lease and property tax payments and employment growth during plant construction and operation. Wind energy represented 2.3 percent of the U.S. electricity supply in 2010, but studies show that penetrations of at least 20 percent are feasible. Several studies have used input-output models to predict direct, indirect, and induced economic development impacts. These analyses have often been completed prior to project construction. Available studies have not yet investigated the economic development impacts of wind development at the county level using post-construction econometric evaluation methods. Analysis of county-level impacts is limited. However, previous county-level analyses have estimated operation-period employment at 0.2 to 0.6 jobs per megawatt (MW) of power installed and earnings at $9,000/MW to $50,000/MW. We find statistically significant evidence of positive impacts of wind development on county-level per capita income from the OLS and …
Date: July 25, 2011
Creator: Brown, J.; Hoen, B.; Lantz, E.; Pender, J. & Wiser, R.
Object Type: Article
System: The UNT Digital Library
LaserFest Celebration (open access)

LaserFest Celebration

LaserFest was the yearlong celebration, during 2010, of the 50th anniversary of the demonstration of the first working laser. The goals of LaserFest were: to highlight the impact of the laser in its manifold commercial, industrial and medical applications, and as a tool for ongoing scientific research; to use the laser as one example that illustrates, more generally, the route from scientific innovation to technological application; to use the laser as a vehicle for outreach, to stimulate interest among students and the public in aspects of physical science; to recognize and honor the pioneers who developed the laser and its many applications; to increase awareness among policymakers of the importance of R&D funding as evidenced by such technology as lasers. One way in which LaserFest sought to meet its goals was to encourage relevant activities at a local level all across the country -- and also abroad -- that would be identified with the larger purposes of the celebration and would carry the LaserFest name. Organizers were encouraged to record and advertise these events through a continually updated web-based calendar. Four projects were explicitly detailed in the proposals: 1) LaserFest on the Road; 2) Videos; 3) Educational material; and 4) …
Date: August 25, 2011
Creator: Chodos, Alan & Rogan, Elizabeth A.
Object Type: Text
System: The UNT Digital Library
Halo Formation And Emittance Growth of Positron Beams in Plasmas (open access)

Halo Formation And Emittance Growth of Positron Beams in Plasmas

An ultrarelativistic 28.5 GeV, 700-{micro}m-long positron bunch is focused near the entrance of a 1.4-m-long plasma with a density n{sub e} between {approx}10{sup 13} and {approx}5 x 10{sup 14} cm{sup -3}. Partial neutralization of the bunch space charge by the mobile plasma electrons results in a reduction in transverse size by a factor of {approx}3 in the high emittance plane of the beam {approx}1 m downstream from the plasma exit. As n{sub e} increases, the formation of a beam halo containing {approx}40% of the total charge is observed, indicating that the plasma focusing force is nonlinear. Numerical simulations confirm these observations. The bunch with an incoming transverse size ratio of {approx}3 and emittance ratio of {approx}5 suffers emittance growth and exits the plasma with approximately equal sizes and emittances.
Date: October 25, 2011
Creator: Muggli, P.; Blue, B. E.; Clayton, C. E.; Decker, F. J.; Hogan, M. J.; Huang, C. et al.
Object Type: Article
System: The UNT Digital Library
Performance Validation and Scaling of a Capillary Membrane Solid-Liquid Separation System (open access)

Performance Validation and Scaling of a Capillary Membrane Solid-Liquid Separation System

Algaeventure Systems (AVS) has previously demonstrated an innovative technology for dewatering algae slurries that dramatically reduces energy consumption by utilizing surface physics and capillary action. Funded by a $6M ARPA-E award, transforming the original Harvesting, Dewatering and Drying (HDD) prototype machine into a commercially viable technology has required significant attention to material performance, integration of sensors and control systems, and especially addressing scaling issues that would allow processing extreme volumes of algal cultivation media/slurry. Decoupling the harvesting, dewatering and drying processes, and addressing the rate limiting steps for each of the individual steps has allowed for the development individual technologies that may be tailored to the specific needs of various cultivation systems. The primary performance metric used by AVS to assess the economic viability of its Solid-Liquid Separation (SLS) dewatering technology is algae mass production rate as a function of power consumption (cost), cake solids/moisture content, and solids capture efficiency. An associated secondary performance metric is algae mass loading rate which is dependent on hydraulic loading rate, area-specific hydraulic processing capacity (gpm/in2), filter:capillary belt contact area, and influent algae concentration. The system is capable of dewatering 4 g/L (0.4%) algae streams to solids concentrations up to 30% with capture efficiencies …
Date: October 25, 2011
Creator: Rogers, S.; Cook, J.; Juratovac, J.; Goodwillie, J.; Burke, T. & Stuart, B., ed.
Object Type: Article
System: The UNT Digital Library
MWRRET Value-Added Product: The Retrieval of Liquid Water Path and Precipitable Water Vapor from Microwave Radiometer (MWR) Data Sets (Revision 2) (open access)

MWRRET Value-Added Product: The Retrieval of Liquid Water Path and Precipitable Water Vapor from Microwave Radiometer (MWR) Data Sets (Revision 2)

This report provides a short description of the Atmospheric Radiation Measurement (ARM) Climate Research Facility microwave radiometer (MWR) Retrieval (MWRRET) value-added product (VAP) algorithm. This algorithm utilizes a complementary physical retrieval method and applies brightness temperature offsets to reduce spurious liquid water path (LWP) bias in clear skies resulting in significantly improved precipitable water vapor (PWV) and LWP retrievals. We present a general overview of the technique, input parameters, output products, and describe data quality checks. A more complete discussion of the theory and results is given in Turner et al. (2007b).
Date: July 25, 2011
Creator: Gaustad, K. L.; Turner, D. D. & McFarlane, S. A.
Object Type: Report
System: The UNT Digital Library
IMPROVEMENT OF CdMnTe DETECTOR PERFORMANCE BY MnTe PURIFICATION (open access)

IMPROVEMENT OF CdMnTe DETECTOR PERFORMANCE BY MnTe PURIFICATION

Residual impurities in manganese (Mn) are a big obstacle to obtaining high-performance CdMnTe (CMT) X-ray and gamma-ray detectors. Generally, the zone-refining method is an effective way to improve the material's purity. In this work, we purified the MnTe compounds combining the zone-refining method with molten Te, which has a very high solubility for most impurities. We confirmed the improved purity of the material by glow-discharge mass spectrometry (GDMS). We also found that CMT crystals from a multiply-refined MnTe source, grown by the vertical Bridgman method, yielded better performing detectors.
Date: April 25, 2011
Creator: Kim, K. H.; Bolotnikov, A. E.; Camarda, G. S.; Tappero, R.; Hossain, A.; Cui, Y. et al.
Object Type: Article
System: The UNT Digital Library
Nonlinear pulse propagation and phase velocity of laser-driven plasma waves (open access)

Nonlinear pulse propagation and phase velocity of laser-driven plasma waves

Laser evolution and plasma wave excitation by a relativistically-intense short-pulse laser in underdense plasma are investigated in the broad pulse limit, including the effects of pulse steepening, frequency red-shifting, and energy depletion. The nonlinear plasma wave phase velocity is shown to be significantly lower than the laser group velocity and further decreases as the pulse propagates owing to laser evolution. This lowers the thresholds for trapping and wavebreaking, and reduces the energy gain and efficiency of laser-plasma accelerators that use a uniform plasma profile.
Date: March 25, 2011
Creator: Schroeder, Carl B.; Benedetti, Carlo; Esarey, Eric & Leemans, Wim
Object Type: Article
System: The UNT Digital Library
MPO B593110 - Final Report (open access)

MPO B593110 - Final Report

National Security Technologies, LLC (NSTec) shall provide one (1) Mechanical Engineer to support the Linear Collider Subsystem Development Program at Lawrence Livermore National Security, LLC (LLNS). The NSTec Mechanical Engineer's efforts will include engineering, design, and drawing support for the Vacuum Seal Test. NSTec will also provide a final report of the setup and input to LLNL's project management on project status. The NSTec Mechanical Engineer's efforts will also include engineering, design, and drawing support to the conceptual design for manufacturing of the Flux Concentrator Magnet. NSTec will also contribute to LLNS's final report on the Flux Concentrator Magnet. The deliverables are drawings, sketches, engineering documents, and final reports delivered to the LLNS Technical Representative.
Date: July 25, 2011
Creator: Brooksby, C
Object Type: Report
System: The UNT Digital Library
Costilla County Biodiesel Pilot Project (open access)

Costilla County Biodiesel Pilot Project

The Costilla County Biodiesel Pilot Project has demonstrated the compatibility of biodiesel technology and economics on a local scale. The project has been committed to making homegrown biodiesel a viable form of community economic development. The project has benefited by reducing risks by building the facility gradually and avoiding large initial outlays of money for facilities and technologies. A primary advantage of this type of community-scale biodiesel production is that it allows for a relatively independent, local solution to fuel production. Successfully using locally sourced feedstocks and putting the fuel into local use emphasizes the feasibility of different business models under the biodiesel tent and that there is more than just a one size fits all template for successful biodiesel production.
Date: August 25, 2011
Creator: Doon, Ben & Quintana, Dan
Object Type: Report
System: The UNT Digital Library
Electronic Structure of CeFeAsO1-xFx (x=0, 0.11/x=0.12) compounds (open access)

Electronic Structure of CeFeAsO1-xFx (x=0, 0.11/x=0.12) compounds

We report an extensive study on the intrinsic bulk electronic structure of the high-temperature superconductor CeFeAsO{sub 0.89}F{sub 0.11} and its parent compound CeFeAsO by soft and hard x-ray photoemission, x-ray absorption and soft-x-ray emission spectroscopies. The complementary surface/bulk probing depth, and the elemental and chemical sensitivity of these techniques allows resolving the intrinsic electronic structure of each element and correlating it with the local structure, which has been probed by extended-x-ray absorption fine structure spectroscopy. The measurements indicate a predominant 4f{sup 1} (i.e. Ce{sup 3+}) initial state configuration for Cerium and an effective valence-band-to-4f charge-transfer screening of the core hole. The spectra also reveal the presence of a small Ce f{sup 0} initial state configuration, which we assign to the occurrence of an intermediate valence state. The data reveal a reasonably good agreement with the partial density of states as obtained in standard density functional calculations over a large energy range. Implications for the electronic structure of these materials are discussed.
Date: January 25, 2011
Creator: Bondino, F.; Magnano, E.; Booth, C. H.; Offi, F.; Panaccione, G.; Malvestuto, M. et al.
Object Type: Article
System: The UNT Digital Library
Novel deflecting cavity design for eRHIC (open access)

Novel deflecting cavity design for eRHIC

To prevent significant loss of the luminosity due to large crossing angle in the future ERL based Electron Ion Collider at BNL (eRHIC), there is a demand for crab cavities. In this article, we will present a novel design of the deflecting/crabbing 181 MHz superconducting RF cavity that will fulfil the requirements of eRHIC. The quarter-wave resonator structure of the new cavity possesses many advantages, such as compact size, high R{sub t}/Q, the absence of the same order mode and lower order mode, and easy higher order mode damping. We will present the properties and characteristics of the new cavity in detail. As the accelerator systems grow in complexity, developing compact and efficient deflecting cavities is of great interest. Such cavities will benefit situations where the beam line space is limited. The future linac-ring type electron-ion collider requires implementation of a crab-crossing scheme for both beams at the interaction region. The ion beam has a long bunches and high rigidity. Therefore, it requires a low frequency, large kicking angle deflector. The frequency of the deflecting mode for the current collider design is 181 MHz, and the deflecting angle is {approx}5 mrad for each beam. At such low frequency, the previous …
Date: July 25, 2011
Creator: Wu, Q.; Belomestnykh, S. & Ben-Zvi, Ilan
Object Type: Article
System: The UNT Digital Library