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15.4% CuIn1-XGaXSe2-Based Photovoltaic Cells from Solution-Based Precursor Films (open access)

15.4% CuIn1-XGaXSe2-Based Photovoltaic Cells from Solution-Based Precursor Films

We have fabricated 15.4%- and 12.4%-efficient CuIn1-XGaXSe2 (CIGS)-based photovoltaic devices from solution-based electrodeposition (ED) and electroless-deposition (EL) precursors. As-deposited precursors are Cu-rich CIGS. Additional In, Ga, and Se are added to the ED and EL precursor films by physical vapor deposition (PVD) to adjust the final film composition to CuIn1-XGaXSe2. The ED and EL device parameters are compared with those of a recent world record, an 18.8%-efficient PVD device. The tools used for comparison are current voltage, capacitance voltage, and spectral response characteristics.
Date: May 25, 1999
Creator: Bhattacharya, R. N.; Batchelor, W.; Contreras, M. A.; Noufi, R. N. (National Renewable Energy Laboratory); Hiltner, J. F. & Sites, J. R. (Department of Physics, Colorado State University)
System: The UNT Digital Library
30 years of high-intensity negative ion sources for accelerators (open access)

30 years of high-intensity negative ion sources for accelerators

Thirty years ago, July 1, 1971, significant enhancement of negative ion emission from a gas discharge following an admixture of cesium was observed for the first time. This observation became the basis for the development of Surface Plasma Sources (SPS) for efficient production of negative ions from the interaction of plasma particles with electrodes on which adsorbed cesium reduced the surface work-function. The emission current density of negative ions increased rapidly from j {approximately} 10 mA/cm{sup 2} to 3.7 A/cm{sup 2} with a flat cathode and up to 8 A/cm{sup 2} with an optimized geometrical focusing in the long pulse SPS, and to 0.3 A/cm{sup 2} for DC SPS, recently increased up to 0.7 A/cm{sup 2}. Discovery of charge-exchange cooling helped decrease the negative ion temperature T below 1 eV, and increase brightness by many orders to a level compatible with the best proton sources, B = j/T> 1 A/cm{sup 2} eV. The combination of the SPS with charge-exchange injection improved large accelerators operation and has permitted beam accumulation up to space-charge limit and overcome this limit several times. The early SPS for accelerators have been in operation without modification for {approximately} 25 years. Advanced version of the SPS for …
Date: July 25, 2001
Creator: Dudnikov, Vadim
System: The UNT Digital Library
1998 Gordon Research Conference on Mutagenesis. Final progress report. (open access)

1998 Gordon Research Conference on Mutagenesis. Final progress report.

This final progress report includes brief comments on the organization of the conference, the conference program, and a list of attendees.
Date: August 25, 1999
Creator: Wallace, Susan & Jiricny, Josef
System: The UNT Digital Library
2004 Atomic and Molecular Interactions Gordon Research Conference (open access)

2004 Atomic and Molecular Interactions Gordon Research Conference

The 2004 Gordon Research Conference on Atomic and Molecular Interactions was held July 11-16 at Colby-Sawyer College, New London, New Hampshire. This latest edition in a long-standing conference series featured invited talks and contributed poster papers on dynamics and intermolecular interactions in a variety of environments, ranging from the gas phase through surfaces and condensed media. A total of 90 conferees participated in the conference.
Date: October 25, 2004
Creator: Dagdigian, Dr. Paul J.
System: The UNT Digital Library
2005 Atomic Physics Gordon Conference, June 26-July 1, 2005 (open access)

2005 Atomic Physics Gordon Conference, June 26-July 1, 2005

This article is a detailed description of the Gordon Research Conference on Atomic Physics.
Date: June 25, 2005
Creator: Monroe, Christopher
System: The UNT Digital Library
2010 INORGANIC CHEMISTRY GORDON RESEARCH CONFERENCE JUNE 20 - 25, 2010 (open access)

2010 INORGANIC CHEMISTRY GORDON RESEARCH CONFERENCE JUNE 20 - 25, 2010

The Inorganic Chemistry GRC is one of the longest-standing of the GRCs, originating in 1951. Over the years, this conference has played a role in spawning many other GRCs in specialized fields, due to the involvement of elements from most of the periodic table. These include coordination, organometallic, main group, f-element, and solid state chemistries; materials science, catalysis, computational chemistry, nanotechnology, bioinorganic, environmental, and biomedical sciences just to name a few. The 2010 Inorganic Chemistry GRC will continue this tradition, where scientists at all levels from academic, industrial, and national laboratories meet to define the important problems in the field and to highlight emerging opportunities through exchange of ideas and discussion of unpublished results. Invited speakers will present on a wide variety of topics, giving attendees a look at areas both inside and outside of their specialized areas of interest. In addition to invited speakers, the poster sessions at GRCs are a key feature of the conference. All conferees at the Inorganic Chemistry GRC are invited to present a poster on their work, and here the informal setting promotes the free exchange of ideas and fosters new relationships. As in previous years, we will offer poster presenters the opportunity to …
Date: June 25, 2010
Creator: LOCKEMEYER, JOHN
System: The UNT Digital Library
2012 MICROBIAL STRESS RESPONSE GORDON RESEARCH CONFERENCE, JULY 20-25, 2012 (open access)

2012 MICROBIAL STRESS RESPONSE GORDON RESEARCH CONFERENCE, JULY 20-25, 2012

The Gordon Research Conference on MICROBIAL STRESS RESPONSE was held at Mount Holyoke College, South Hadley, Massachusetts, July 15-20, 2012. The Conference was well-attended with 180 participants. The 2012 Microbial Stress Responses Gordon Research Conference will provide a forum for the open reporting of recent discoveries on the diverse mechanisms employed by microbes to respond to stress. Approaches range from analysis at the molecular level (how are signals perceived and transmitted to change gene expression or function) to cellular and microbial community responses. Gordon Research Conferences does not permit publication of meeting proceedings.
Date: July 25, 2012
Creator: Donohue, Timothy
System: The UNT Digital Library
2013 METALS IN BIOLOGY GORDON RESEARCH CONFERENCE, JANUARY 20-25, 2013 (open access)

2013 METALS IN BIOLOGY GORDON RESEARCH CONFERENCE, JANUARY 20-25, 2013

Typical topics for lectures and posters include: biochemical and biophysical characterization of new metal containing proteins, enzymes, nucleic acids, factors, and chelators from all forms of life; synthesis, detailed characterization, and reaction chemistry of biomimetic compounds; novel crystal and solution structures of biological molecules and synthetic metal-chelates; discussions of the roles that metals play in medicine, maintenance of the environment, and biogeochemical processes; metal homeostasis; application of theory and computations to the structure and mechanism of metal-containing biological systems; and novel applications of spectroscopy to metals in biological systems.
Date: January 25, 2013
Creator: Rosenzweig, Amy
System: The UNT Digital Library
30th Actinide Separations Conference, PNNL-SA-50126 (open access)

30th Actinide Separations Conference, PNNL-SA-50126

Program booklet for the 30th Actinide Separations Conference. Contains agenda and abstracts for 27 poster and 38 oral presentations to be made during the 3-day meeting, May 23-25, 2006.
Date: May 25, 2006
Creator: Delegard, Calvin H.
System: The UNT Digital Library
The (3He,tf) as a surrogate reaction to determine (n,f) cross sections in the 10 to 20 MeV energy range (open access)

The (3He,tf) as a surrogate reaction to determine (n,f) cross sections in the 10 to 20 MeV energy range

The surrogate reaction 238U(3He,tf) is used to determine the 237Np(n,f) cross section indirectly over an equivalent neutron energy range from 10 to 20 MeV. A self-supporting ~;;761 mu g/cm2 metallic 238U foil was bombarded with a 42 MeV 3He2+ beam from the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory (LBNL). Outgoing charged particles and fission fragments were identified using the Silicon Telescope Array for Reaction Studies (STARS), consists of two 140 mu m and one 1000 mu m Micron S2 type silicon detectors. The 237Np(n,f) cross sections, determined indirectly, were compared with the 237Np(n,f) cross section data from direct measurements, the Evaluated Nuclear Data File (ENDF/B-VII.0), and the Japanese Evaluated Nuclear Data Library (JENDL 3.3) and found to closely follow those datasets. Use of the (3He,tf) reaction as a surrogate to extract (n,f) cross section in the 10 to 20 MeV equivalent neutron energy is found to be suitable.
Date: February 25, 2009
Creator: Basunia, M. S.; Clark, R. M.; Goldblum, B. L.; Bernstein, L. A.; Phair, L.; Burke, J. T. et al.
System: The UNT Digital Library
Ab initio calculations of the charge state of stopping in a finite-temperature target (open access)

Ab initio calculations of the charge state of stopping in a finite-temperature target

A calculation was made of the time dependent charge state of a heavy projectile traversing a finite-temperature target. The calculation uses an average-atom model to integrate the rate equations.
Date: March 25, 1982
Creator: Bailey, D.; Lee, Y. T. & More, R. M.
System: The UNT Digital Library
Ab initio Molecular Dynamics Simulations of Water Under Static and Shock Compressed Conditions (open access)

Ab initio Molecular Dynamics Simulations of Water Under Static and Shock Compressed Conditions

We report herein a series of ab initio simulations of water under both static and shocked conditions. We have calculated the coherent x-ray scattering intensity of several phases of water under high pressure, using ab initio Density Functional Theory (DFT). We provide new atomic scattering form factors for water at extreme conditions, which take into account frequently neglected changes in ionic charge and electron delocalization. We have also simulated liquid water undergoing shock loading of velocities from 5-11 km/s using the Multi-Scale Shock Technique (MSST). We show that Density Functional Theory (DFT) molecular dynamics results compare extremely well to experiments on the water shock Hugoniot.
Date: July 25, 2007
Creator: Goldman, N; Fried, L E; Mundy, C J; Kuo, I W; Curioni, A & Reed, E
System: The UNT Digital Library
Absolute Measurement of the Polarization of High Energy Proton Beams at RHIC (open access)

Absolute Measurement of the Polarization of High Energy Proton Beams at RHIC

The spin physics program at the Relativistic Heavy Ion Collider (RHIC) requires knowledge of the beam polarization to better than 5%. Such a goal is made the more difficult by the lack of knowledge of the analyzing power of high energy nuclear physics processes. To overcome this, a polarized hydrogen jet target was constructed and installed at one intersection region in RHIC where it intersects both beams and utilizes the precise knowledge of the jet atomic hydrogen beam polarization to measure the analyzing power in proton-proton elastic scattering in the Nuclear Coulomb Interference (CNI) region at the prescribed RHIC proton beam energy. The reverse reaction is used to assess the absolute beam polarization. Simultaneous measurements taken with fast high statistics polarimeters that measure the p-Carbon elastic scattering process also in the CNI region use the jet results to calibrate the latter.
Date: June 25, 2007
Creator: Makdisi, Y.; Bravar, A. Bunce, G. Gill, R.; Huang, H. & AL., ET
System: The UNT Digital Library
ABSORBING WIPP BRINES: A TRU WASTE DISPOSAL STRATEGY (open access)

ABSORBING WIPP BRINES: A TRU WASTE DISPOSAL STRATEGY

Los Alamos National Laboratory (LANL) has completed experiments involving 15 each, 250- liter experimental test containers of transuranic (TRU) heterogeneous waste immersed in two types of brine similar to those found in the underground portion of the Waste Isolation Pilot Plant (WIPP). To dispose of the waste without removing the brine from the test containers, LANL added commercially available cross-linked polyacrylate granules to absorb the 190 liters of brine in each container, making the waste compliant for shipping to the WIPP in a Standard Waste Box (SWB). Prior to performing the absorption, LANL and the manufacturer of the absorbent conducted laboratory and field tests to determine the ratio of absorbent to brine that would fully absorb the liquid. Bench scale tests indicated a ratio of 10 parts Castile brine to one part absorbent and 6.25 parts Brine A to one part absorbent. The minimum ratio of absorbent to brine was sought because headspace in the containers was limited. However, full scale testing revealed that the ratio should be adjusted to be about 15% richer in absorbent. Additional testing showed that the absorbent would not apply more than 13.8 kPa pressure on the walls of the vessel and that the absorbent …
Date: February 25, 2002
Creator: Yeamans, D. R. & Wrights, R. S.
System: The UNT Digital Library
Accelerating Polarized Protons to 250 GEV (open access)

Accelerating Polarized Protons to 250 GEV

The Relativistic Heavy Ion Collider (RHIC) as the first high energy polarized proton collider was designed t o provide polarized proton collisions a t a maximum beam energy of 250 GeV. I t has been providing collisions a t a beam energy of 100 Gel' since 2001. Equipped with two full Siberian snakes in each ring, polarization is preserved during the acceleration from injection to 100 GeV with careful control of the betatron tunes and the vertical orbit distortions. However, the intrinsic spin resonances beyond 100 GeV are about a factor of two stronger than those below 100 GeV? making it important t o examine the impact of these strong intrinsic spin resonances on polarization survival and the tolerance for vertical orbit distortions. Polarized protons were accelerated t o the record energy of 250 GeV in RHIC with a polarization of 46% measured a t top energy in 2006. The polarization measurement as a function of beam energy also shows some polarization loss around 136 GeV, the first strong intrinsic resonance above 100 GeV. This paper presents the results and discusses the sensitivity of the polarization survival t o orbit distortions.
Date: June 25, 2007
Creator: Bai, M.; Ahrens, L.; Alekseev, I. G.; Alessi, J.; Beebe-Wang, J. & AL., ET
System: The UNT Digital Library
Acceleration of Electrons With the Racetrack Non-Scaling Ffag for E-Rhic (open access)

Acceleration of Electrons With the Racetrack Non-Scaling Ffag for E-Rhic

The future relativistic electron hadron collider: e-RHIC requires acceleration of electrons to 10 GeV. In the case that the super conducting linac is selected for acceleration, an energy recovery scheme is required. We propose to study a possibility of using the non-scaling Fixed-Field Gradient-Accelerator (NS-FFAG) for different energies. The beam will be accelerated by the superconducting linac at the top of the sine function, brought back to the front of the linac by the non-scaling FFAG and repeating this few times until the total energy of 20 GeV is reached. After collisions the beam is brought back by the non-scaling FFAG and decelerated (on the lower RF phase) in the same sequence but in the reverse order. Conventional and non-conventional beam dynamic issues will be discussed, like the transit time matching effect and the time of flight adjustments.
Date: June 25, 2007
Creator: Trbojevic, D.; Blaskiewicz, M.; Litvinenko, V.; Ptitsyn, V. & Roser, T.
System: The UNT Digital Library
Accelerator Production Options for 99MO (open access)

Accelerator Production Options for 99MO

Shortages of {sup 99}Mo, the most commonly used diagnostic medical isotope, have caused great concern and have prompted numerous suggestions for alternate production methods. A wide variety of accelerator-based approaches have been suggested. In this paper we survey and compare the various accelerator-based approaches.
Date: August 25, 2010
Creator: Bertsche, Kirk
System: The UNT Digital Library
Accuracy Limitations in Long Trace Profilometry (open access)

Accuracy Limitations in Long Trace Profilometry

As requirements for surface slope error quality of grazing incidence optics approach the 100 nanoradian level, it is necessary to improve the performance of the measuring instruments to achieve accurate and repeatable results at this level. We have identified a number of internal error sources in the Long Trace Profiler (LTP) that affect measurement quality at this level. The LTP is sensitive to phase shifts produced within the millimeter diameter of the pencil beam probe by optical path irregularities with scale lengths of a fraction of a millimeter. We examine the effects of mirror surface ''macroroughness'' and internal glass homogeneity on the accuracy of the LTP through experiment and theoretical modeling. We will place limits on the allowable surface ''macroroughness'' and glass homogeneity required to achieve accurate measurements in the nanoradian range.
Date: August 25, 2003
Creator: Takacs, P. Z. & Qian, S.
System: The UNT Digital Library
Accurate Computer Simulation of a Drift Chamber (open access)

Accurate Computer Simulation of a Drift Chamber

A general purpose program for drift chamber studies is described. First the capacitance matrix is calculated using a Green's function technique. The matrix is used in a linear-least-squares fit to choose optimal operating voltages. Next the electric field is computed, and given knowledge of gas parameters and magnetic field environment, a family of electron trajectories is determined. These are finally used to make drift distance vs time curves which may be used directly by a track reconstruction program. Results are compared with data obtained from the cylindrical chamber in the Axial Field Magnet experiment at the CERN ISR.
Date: March 25, 1980
Creator: Killian, T J
System: The UNT Digital Library
Achieving closure at Fernald (open access)

Achieving closure at Fernald

When Fluor Fernald took over the management of the Fernald Environmental Management Project in 1992, the estimated closure date of the site was more than 25 years into the future. Fluor Fernald, in conjunction with DOE-Fernald, introduced the Accelerated Cleanup Plan, which was designed to substantially shorten that schedule and save taxpayers more than $3 billion. The management of Fluor Fernald believes there are three fundamental concerns that must be addressed by any contractor hoping to achieve closure of a site within the DOE complex. They are relationship management, resource management and contract management. Relationship management refers to the interaction between the site and local residents, regulators, union leadership, the workforce at large, the media, and any other interested stakeholder groups. Resource management is of course related to the effective administration of the site knowledge base and the skills of the workforce, the attraction and retention of qualified a nd competent technical personnel, and the best recognition and use of appropriate new technologies. Perhaps most importantly, resource management must also include a plan for survival in a flat-funding environment. Lastly, creative and disciplined contract management will be essential to effecting the closure of any DOE site. Fluor Fernald, together with …
Date: February 25, 2001
Creator: Bradburne, John & Patton, Tisha C.
System: The UNT Digital Library
Actinide Measurements by Accelerator Mass Spectrometry at Lawrence Livermore National Laboratory (open access)

Actinide Measurements by Accelerator Mass Spectrometry at Lawrence Livermore National Laboratory

We report on the development of an accelerator mass spectrometry (AMS) system for the measurement of actinides at Lawrence Livermore National Laboratory. This AMS system is centered on a recently completed heavy isotope beam line that was designed particularly for high sensitivity, robust, high-throughput measurements of actinide concentrations and isotopic ratios. A fast isotope switching capability has been incorporated in the system, allowing flexibility in isotope selection and for the quasi-continuous normalization to a reference isotope spike. Initially, our utilization of the heavy isotope system has concentrated on the measurement of Pu isotopes. Under current operating conditions, background levels equivalent to {approx}1 x 10{sup 5} atoms are observed during routine {sup 239}Pu and {sup 240}Pu measurements. Measurements of samples containing {approx}10{sup 13} {sup 238}U atoms demonstrate that the system provides a {sup 238}U rejection factor during {sup 239}Pu measurements of {approx}10{sup 7}. Measurements of known materials, combined with results from an externally organized inter-comparison program, indicate that our {sup 239}Pu measurements are accurate and precise down to the {micro}Bq level ({approx}10{sup 6} atoms). Recently, we have investigated the performance of our heavy isotope AMS system in measurements of {sup 237}Np and {sup 236}U. Results of these investigations are discussed. The …
Date: September 25, 2003
Creator: Brown, T A; Marchetti, A A; Martinelli, R E; Cox, C C; Knezovich, J P & Hamilton, T F
System: The UNT Digital Library
Activation Energy of Tantalum-Tungsten Oxide Thermite Reaction (open access)

Activation Energy of Tantalum-Tungsten Oxide Thermite Reaction

The activation energy of a high melting temperature sol-gel (SG) derived tantalum-tungsten oxide thermite composite was determined using the Kissinger isoconversion method. The SG derived powder was consolidated using the High Pressure Spark Plasma Sintering (HPSPS) technique to 300 and 400 C to produce pellets with dimensions of 5 mm diameter by 1.5 mm height. A custom built ignition setup was developed to measure ignition temperatures at high heating rates (500-2000 C {center_dot} min{sup -1}). Such heating rates were required in order to ignite the thermite composite. Unlike the 400 C samples, results show that the samples consolidated to 300 C undergo an abrupt change in temperature response prior to ignition. This change in temperature response has been attributed to the crystallization of the amorphous WO{sub 3} in the SG derived Ta-WO{sub 3} thermite composite and not to a pre-ignition reaction between the constituents. Ignition temperatures for the Ta-WO{sub 3} thermite ranged from approximately 465-670 C. The activation energy of the SG derived Ta-WO{sup 3} thermite composite consolidated to 300 and 400 C were determined to be 37.787 {+-} 1.58 kJ {center_dot} mol{sup -1} and 57.381 {+-} 2.26 kJ {center_dot} mol{sup -1}, respectively.
Date: February 25, 2010
Creator: Cervantes, O.; Kuntz, J.; Gash, A. & Munir, Z.
System: The UNT Digital Library
Adaptive Remote-Sensing Techniques Implementing Swarms of Mobile Agents (open access)

Adaptive Remote-Sensing Techniques Implementing Swarms of Mobile Agents

In many situations, stand-off remote-sensing and hazard-interdiction techniques over realistic operational areas are often impractical "and difficult to characterize. An alternative approach is to implement an adap- tively deployable array of sensitive agent-specific devices. Our group has been studying the collective be- havior of an autonomous, multi-agent system applied to chedbio detection and related emerging threat applications, The current physics-based models we are using coordinate a sensor array for mukivanate sig- nal optimization and coverage as re,alized by a swarm of robots or mobile vehicles. These intelligent control systems integrate'glob"ally operating decision-making systems and locally cooperative learning neural net- works to enhance re+-timp operational responses to dynarnical environments examples of which include obstacle avoidance, res~onding to prevailing wind patterns, and overcoming other natural obscurants or in- terferences. Collectively',tkensor nefirons with simple properties, interacting according to basic community rules, can accomplish complex interconnecting functions such as generalization, error correction, pattern recognition, sensor fusion, and localization. Neural nets provide a greater degree of robusmess and fault tolerance than conventional systems in that minor variations or imperfections do not impair performance. The robotic platforms would be equipped with sensor devices that perform opticaI detection of biologicais in combination with multivariate chemical analysis tools …
Date: November 25, 1998
Creator: Asher, R. B.; Cameron, S. M.; Loubriel, G. M.; Robinett, R. D.; Stantz, K. M.; Trahan, M. W. et al.
System: The UNT Digital Library
The adaptive x-ray optics project at the Lawrence Livermore National Laboratory (open access)

The adaptive x-ray optics project at the Lawrence Livermore National Laboratory

None
Date: June 25, 2013
Creator: Pardini, T; Poyneer, L A; McCarville, T J; Macintosh, B; Bauman, B & Pivovaroff, M J
System: The UNT Digital Library