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The Analysis of Thin Wires Using Higher-Order Elements and Basis Functions (open access)

The Analysis of Thin Wires Using Higher-Order Elements and Basis Functions

Thin wire analysis was applied to curved wire segments in [1], but a special procedure was needed to evaluate the self and near-self terms. The procedure involved associating the singular behavior with a straight segment tangent to the curved source segment, permitting use of algorithms for straight wires. Recently, a procedure that avoids the singularity extraction for straight wires was presented in [2-4]. In this paper, the approach in [4] is applied to curved (or higher-order) wires using a procedure similar to that used in [1] for singularity extraction. Here, the straight tangent segment is used to determine the quadrature rules to be used on the curved segment. The result is a formulation that allows for a general mixture of higher-order basis functions [5] and higher-order wire segments.
Date: January 23, 2006
Creator: Champagne, N. J.; Wilton, D. R. & Rockway, J. W.
System: The UNT Digital Library
GIFFT: A Fast Solver for Modeling Sources in a Metamaterial Environment of Finite Size (open access)

GIFFT: A Fast Solver for Modeling Sources in a Metamaterial Environment of Finite Size

Due to the recent explosion of interest in studying the electromagnetic behavior of large (truncated) periodic structures such as phased arrays, frequency-selective surfaces, and metamaterials, there has been a renewed interest in efficiently modeling such structures. Since straightforward numerical analyses of large, finite structures (i.e., explicitly meshing and computing interactions between all mesh elements of the entire structure) involve significant memory storage and computation times, much effort is currently being expended on developing techniques that minimize the high demand on computer resources. One such technique that belongs to the class of fast solvers for large periodic structures is the GIFFT algorithm (Green's function interpolation and FFT), which is first discussed in [1]. This method is a modification of the adaptive integral method (AIM) [2], a technique based on the projection of subdomain basis functions onto a rectangular grid. Like the methods presented in [3]-[4], the GIFFT algorithm is an extension of the AIM method in that it uses basis-function projections onto a rectangular grid through Lagrange interpolating polynomials. The use of a rectangular grid results in a matrix-vector product that is convolutional in form and can thus be evaluated using FFTs. Although our method differs from [3]-[6] in various respects, …
Date: January 23, 2006
Creator: Capolino, F; Basilio, L; Fasenfest, B J & Wilton, D R
System: The UNT Digital Library
Introduction to special section on Hydrologic Synthesis (open access)

Introduction to special section on Hydrologic Synthesis

The Hydrological Synthesis special section presentssynthesis topics that have the potential to revolutionize hydrologicalsciences in a manner needed to meet critical water challenges that we nowface. The special section also highlights topics that are important andexciting enough to compel researchers to engage in collaborativesynthesis activities. This introductory paper provides a brief overviewof nine papers that are included in this special section, which discussthe synthesis of tools, data, concepts, theories, or approaches acrossdisciplines and scales. The wide range of topics that are exploredinclude groundwater quality, river restoration, water management,nitrogen cycling, and Earth surface dynamics. Collectively, the specialsection papers illustrate that the challenge to deal effectively withcomplex water problems is not purely a scientific, technological, orsocioeconomic one; it is instead a complex, 21st century problem thatrequires coordinated synthesis.
Date: January 23, 2006
Creator: Hubbard, Susan
System: The UNT Digital Library
The National Center for Biomedical Ontology: Advancing Biomedicinethrough Structured Organization of Scientific Knowledge (open access)

The National Center for Biomedical Ontology: Advancing Biomedicinethrough Structured Organization of Scientific Knowledge

The National Center for Biomedical Ontology (http://bioontology.org) is a consortium that comprises leading informaticians, biologists, clinicians, and ontologists funded by the NIH Roadmap to develop innovative technology and methods that allow scientists to record, manage, and disseminate biomedical information and knowledge in machine-processable form. The goals of the Center are: (1) to help unify the divergent and isolated efforts in ontology development by promoting high quality open-source, standards-based tools to create, manage, and use ontologies, (2) to create new software tools so that scientists can use ontologies to annotate and analyze biomedical data, (3) to provide a national resource for the ongoing evaluation, integration, and evolution of biomedical ontologies and associated tools and theories in the context of driving biomedical projects (DBPs), and (4) to disseminate the tools and resources of the Center and to identify, evaluate, and communicate best practices of ontology development to the biomedical community. The Center is working toward these objectives by providing tools to develop ontologies and to annotate experimental data, and by developing resources to integrate and relate existing ontologies as well as by creating repositories of biomedical data that are annotated using those ontologies. The Center is providing training workshops in ontology design, …
Date: January 23, 2006
Creator: Rubin, Daniel L.; Lewis, Suzanna E.; Mungall, Chris J.; Misra,Sima; Westerfield, Monte; Ashburner, Michael et al.
System: The UNT Digital Library
New Applications of Gamma Spectroscopy: Characterization Tools for D&D Process Development, Inventory Reduction Planning & Shipping, Safety Analysis & Facility Management During the Heavy Element Facility Risk Reduction Program (open access)

New Applications of Gamma Spectroscopy: Characterization Tools for D&D Process Development, Inventory Reduction Planning & Shipping, Safety Analysis & Facility Management During the Heavy Element Facility Risk Reduction Program

Novel applications of gamma ray spectroscopy for D&D process development, inventory reduction, safety analysis and facility management are discussed in this paper. These applications of gamma spectroscopy were developed and implemented during the Risk Reduction Program (RPP) to successfully downgrade the Heavy Element Facility (B251) at Lawrence Livermore National Laboratory (LLNL) from a Category II Nuclear Facility to a Radiological Facility. Non-destructive assay in general, gamma spectroscopy in particular, were found to be important tools in project management, work planning, and work control (''Expect the unexpected and confirm the expected''), minimizing worker dose, and resulted in significant safety improvements and operational efficiencies. Inventory reduction activities utilized gamma spectroscopy to identify and confirm isotopics of legacy inventory, ingrowth of daughter products and the presence of process impurities; quantify inventory; prioritize work activities for project management; and to supply information to satisfy shipper/receiver documentation requirements. D&D activities utilize in-situ gamma spectroscopy to identify and confirm isotopics of legacy contamination; quantify contamination levels and monitor the progress of decontamination efforts; and determine the point of diminishing returns in decontaminating enclosures and glove boxes containing high specific activity isotopes such as {sup 244}Cm and {sup 238}Pu. In-situ gamma spectroscopy provided quantitative comparisons of several …
Date: January 23, 2006
Creator: Mitchell, M.; Anderson, B.; Gray, L.; Vellinger, R.; West, M.; Gaylord, R. et al.
System: The UNT Digital Library
Pressure effect on the electronic structure of iron in (Mg,Fe)(Al,Si)O3 perovskite: A combined synchrotron M?ssbauer and x-ray emission spectroscopy study up to 100 GPa (open access)

Pressure effect on the electronic structure of iron in (Mg,Fe)(Al,Si)O3 perovskite: A combined synchrotron M?ssbauer and x-ray emission spectroscopy study up to 100 GPa

We investigated the valence and spin state of iron in an Al-bearing ferromagnesian silicate perovskite sample, (Mg{sub 0.88}Fe{sub 0.09})(Si{sub 0.94}Al{sub 0.10})O{sub 3}, at 300 K and up to 100 GPa, using diamond-anvil cells and synchrotron Moessbauer spectroscopy techniques. Under elevated pressures, our Moessbauer time spectra are sufficiently fitted by a ''three-doublet'' model, which assumes two ferrous (Fe{sup 2+}) iron types and one ferric (Fe{sup 3+}) iron type with distinct hyperfine parameters. At pressures above 20 GPa, the fraction of the ferric iron, Fe{sup 3+}/{Sigma}Fe, is about 75% and remains unchanged to the highest pressure, indicating a fixed valence state of iron within this pressure range. Between 20 and 100 GPa, the quadruple splittings of all three iron types do not change with pressure, while the isomer shift between the Fe{sup 3+} types and the Fe{sup 2+} type increases continuously with increasing pressure. In conjunction with previous x-ray emission data on the same sample, the unchanging quadruple splittings and increasing isomer shift suggest that Fe{sup 2+} undergoes a broad spin crossover towards the low-spin state at 100 GPa, while Fe{sup 3+} remains in the high-spin state. The essentially constant quadruple splittings of Fe{sup 2+} can also be taken as an indication …
Date: January 23, 2006
Creator: Li, J.; Sturhahn, W.; Jackson, J.; Struzhkin, V. V.; Lin, J. F.; Zhao, J. et al.
System: The UNT Digital Library
PROGRESS & CHALLENGES IN CLEANUP OF HANFORDS TANK WASTES (open access)

PROGRESS & CHALLENGES IN CLEANUP OF HANFORDS TANK WASTES

The River Protection Project (RPP), which is managed by the Department of Energy (DOE) Office of River Protection (ORP), is highly complex from technical, regulatory, legal, political, and logistical perspectives and is the largest ongoing environmental cleanup project in the world. Over the past three years, ORP has made significant advances in its planning and execution of the cleanup of the Hartford tank wastes. The 149 single-shell tanks (SSTs), 28 double-shell tanks (DSTs), and 60 miscellaneous underground storage tanks (MUSTs) at Hanford contain approximately 200,000 m{sup 3} (53 million gallons) of mixed radioactive wastes, some of which dates back to the first days of the Manhattan Project. The plan for treating and disposing of the waste stored in large underground tanks is to: (1) retrieve the waste, (2) treat the waste to separate it into high-level (sludge) and low-activity (supernatant) fractions, (3) remove key radionuclides (e.g., Cs-137, Sr-90, actinides) from the low-activity fraction to the maximum extent technically and economically practical, (4) immobilize both the high-level and low-activity waste fractions by vitrification, (5) interim store the high-level waste fraction for ultimate disposal off-site at the federal HLW repository, (6) dispose the low-activity fraction on-site in the Integrated Disposal Facility (IDF), …
Date: January 23, 2006
Creator: HEWITT, W.M. & SCHEPENS, R.
System: The UNT Digital Library
Beyond Boltzmann-Gibbs statistics: Maximum entropy hyperensemblesout-of-equilibrium (open access)

Beyond Boltzmann-Gibbs statistics: Maximum entropy hyperensemblesout-of-equilibrium

What is the best description that we can construct of athermodynamic system that is not in equilibrium, given only one, or afew, extra parameters over and above those needed for a description ofthe same system at equilibrium? Here, we argue the most appropriateadditional parameter is the non-equilibrium entropy of the system, andthat we should not attempt to estimate the probability distribution ofthe system, but rather the metaprobability (or hyperensemble) that thesystem is described by a particular probability distribution. The resultis an entropic distribution with two parameters, one a non-equilibriumtemperature, and the other a measure of distance from equilibrium. Thisdispersion parameter smoothly interpolates between certainty of acanonical distribution at equilibrium and great uncertainty as to theprobability distribution as we move away from equilibrium. We deducethat, in general, large, rare fluctuations become far more common as wemove away from equilibrium.
Date: February 23, 2006
Creator: Crooks, Gavin E.
System: The UNT Digital Library
Comparison of two- and three-dimensional simulations of miscible Rayleigh-Taylor instability (open access)

Comparison of two- and three-dimensional simulations of miscible Rayleigh-Taylor instability

A comparison of two-dimensional and three-dimensional high-resolution numerical large-eddy simulations of planar, miscible Rayleigh-Taylor instability flows are presented. The resolution of the three-dimensional simulation is sufficient to attain a fully turbulent state. A number of different statistics from the mixing region (e.g., growth rates, PDFs, mixedness measures, and spectra) are used to demonstrate that two-dimensional flow simulations differ substantially from the three-dimensional one. It is found that the two-dimensional flow grows more quickly than its three-dimensional counterpart at late times, develops larger structures, and is much less well mixed. These findings are consistent with the concept of inverse cascade in two-dimensional flow, as well as the influence of a reduced effective Atwood number on miscible flow.
Date: February 23, 2006
Creator: Cabot, W
System: The UNT Digital Library
Hydrogen Technology at the Savannah River National Laboratory, Center for Hydrogen Research (CHR) (open access)

Hydrogen Technology at the Savannah River National Laboratory, Center for Hydrogen Research (CHR)

None
Date: February 23, 2006
Creator: Danko, Edward T.
System: The UNT Digital Library
International Symposium on Site Characterization for CO2Geological Storage (open access)

International Symposium on Site Characterization for CO2Geological Storage

Several technological options have been proposed to stabilize atmospheric concentrations of CO{sub 2}. One proposed remedy is to separate and capture CO{sub 2} from fossil-fuel power plants and other stationary industrial sources and to inject the CO{sub 2} into deep subsurface formations for long-term storage and sequestration. Characterization of geologic formations for sequestration of large quantities of CO{sub 2} needs to be carefully considered to ensure that sites are suitable for long-term storage and that there will be no adverse impacts to human health or the environment. The Intergovernmental Panel on Climate Change (IPCC) Special Report on Carbon Dioxide Capture and Storage (Final Draft, October 2005) states that ''Site characterization, selection and performance prediction are crucial for successful geological storage. Before selecting a site, the geological setting must be characterized to determine if the overlying cap rock will provide an effective seal, if there is a sufficiently voluminous and permeable storage formation, and whether any abandoned or active wells will compromise the integrity of the seal. Moreover, the availability of good site characterization data is critical for the reliability of models''. This International Symposium on Site Characterization for CO{sub 2} Geological Storage (CO2SC) addresses the particular issue of site characterization …
Date: February 23, 2006
Creator: Tsang, Chin-Fu
System: The UNT Digital Library
Laser light Backscatter from Intermediate and High Z plasmas (open access)

Laser light Backscatter from Intermediate and High Z plasmas

None
Date: February 23, 2006
Creator: Berger, R L; Constantin, C; Divol, L; Meezan, N; Froula, D H; Glenzer, S H et al.
System: The UNT Digital Library
Myths and Misconceptions in Fall Protection (open access)

Myths and Misconceptions in Fall Protection

Since 1973, when OSHA CFRs 1910 and 1926 began to influence the workplace, confusion about the interpretation of the standards has been a problem and fall protection issues are among them. This confusion is verified by the issuance of 351 (as of 11/25/05) Standard Interpretations issued by OSHA in response to formally submitted questions asking for clarification. Over the years, many workers and too many ES&H Professionals have become 'self-interpreters', reaching conclusions that do not conform to either the Standards or the published Interpretations. One conclusion that has been reached by the author is that many ES&H Professionals are either not aware of, or do not pay attention to the Standard Interpretations issued by OSHA, or the State OSHA interpretation mechanism, whoever has jurisdiction. If you fall in this category, you are doing your organization or clients a disservice and are not providing them with the best information available. Several myths and/or misconceptions have been promulgated to the point that they become accepted fact, until an incident occurs and OSHA becomes involved. For example, one very pervasive myth is that you are in compliance as long as you maintain a distance of 6 feet from the edge. No such carte …
Date: February 23, 2006
Creator: Epp, R. J.
System: The UNT Digital Library
On the work distribution for the adiabatic compression of a diluteclassical gas (open access)

On the work distribution for the adiabatic compression of a diluteclassical gas

We consider the adiabatic and quasi-static compression of adilute classical gas, confined in a piston and initially equilibratedwith a heat bath. We find that the work performed during this process isdescribed statistically by a gamma distribution. We use this result toshow that the model satisfies the non-equilibrium work and fluctuationtheorems, but not the fluctation-dissipation relation. We discuss therare but dominant realizations that contribute most to the exponentialaverage of the work, and relate our results to potentially universal workdistributions.
Date: February 23, 2006
Creator: Crooks, Gavin E. & Jarzynski, Christopher
System: The UNT Digital Library
Oxygen Atom Transfer Energetics: Assessment of the Effect of Method and Solvent (open access)

Oxygen Atom Transfer Energetics: Assessment of the Effect of Method and Solvent

This article discusses oxygen atom transfer energetics.
Date: February 23, 2006
Creator: Dinescu, Adriana; Whiteley, Clinton; Combs, Rachel R. & Cundari, Thomas R., 1964-
System: The UNT Digital Library
Space-charge transport limits of ion beams in periodic quadrupolefocusing channels (open access)

Space-charge transport limits of ion beams in periodic quadrupolefocusing channels

It has been empirically observed in both experiments and particle-in-cell simulations that space-charge-dominated beams suffer strong growth in statistical phase-space area (degraded quality) and particle losses in alternating gradient quadrupole transport channels when the undepressed phase advance {sigma}{sub 0} increases beyond about 85{sup o} per lattice period. Although this criterion has been used extensively in practical designs of strong focusing intense beam transport lattices, the origin of the limit has not been understood. We propose a mechanism for the transport limit resulting from classes of halo particle resonances near the core of the beam that allow near-edge particles to rapidly increase in oscillation amplitude when the space-charge intensity and the utter of the matched beam envelope are both sufficiently large. When coupled with a diffuse beam edge and/or perturbations internal to the beam core that can drive particles outside the edge, this mechanism can result in large and rapid halo-driven increases in the statistical phase-space area of the beam, lost particles, and degraded transport. A core-particle model is applied to parametrically analyze this process. Extensive self-consistent particle in cell simulations are employed to better quantify properties of the space-charge limits and to verify core-particle model predictions.
Date: February 23, 2006
Creator: Lund, S. M. & Chawla, S. R.
System: The UNT Digital Library
Effects of Natural Environmental Changes on Soil-Vapor Extraction Rates (open access)

Effects of Natural Environmental Changes on Soil-Vapor Extraction Rates

Remediation by soil-vapor extraction has been used for over a decade at Lawrence Livermore National Laboratory (LLNL). We have found that natural changes in environmental conditions affect the rate of soil-vapor extraction. Data on flow rate observations collected over this time are compared to in-situ measurements of several different environmental parameters (soil-gas pressure, soil-temperature, soil-moisture, Electrical Resistance Tomography (ERT), rainfall and barometric pressure). Environmental changes that lead to increased soil-moisture are associated with reduced soil-vapor extraction flow rates. We have found that the use of higher extraction vacuums combined with dual-phase extraction can help to increase pneumatic conductivity when vadose zone saturation is a problem. Daily changes in barometric pressure and soil-gas temperature were found to change flow rate measurements by as much as 10% over the course of a day.
Date: March 23, 2006
Creator: Martins, S. & Gregory, S.
System: The UNT Digital Library
Influence of argon and oxygen on charge-state-resolved ion energydistributions of filtered aluminum arcs (open access)

Influence of argon and oxygen on charge-state-resolved ion energydistributions of filtered aluminum arcs

The charge-state-resolved ion energy distributions (IEDs) in filtered aluminum vacuum arc plasmas were measured and analyzed at different oxygen and argon pressures in the range 0.5 8.0 mTorr. A significant reduction of the ion energy was detected as the pressure was increased, most pronounced in an argon environment and for the higher charge states. The corresponding average charge state decreased from 1.87 to 1.0 with increasing pressure. The IEDs of all metal ions in oxygen were fitted with shifted Maxwellian distributions. The results show that it is possible to obtain a plasma composition with a narrow charge-state distribution as well as a narrow IED. These data may enable tailoring thin-film properties through selecting growth conditions that are characterized by predefined charge state and energy distributions.
Date: March 23, 2006
Creator: Rosen, Johanna; Anders, Andre; Mraz, Stanislav; Atiser, Adil & Schneider, Jochen M.
System: The UNT Digital Library
Nano-subgrain Strengthening in Ball-milled Iron (open access)

Nano-subgrain Strengthening in Ball-milled Iron

The strength and deformation behavior of ball-milled, iron-base materials containing nano-scale subgrains have been evaluated. As reported by several authors, nanosubgrains form during the early stages of ball milling as a result of severe plastic deformation inherent in the ball milling process. The strength for these nano-scale subgrains are compared with the strength of larger-scale subgrains in iron and iron-base alloys produced by traditional mechanical working. The data covers over 2 orders of magnitude in subgrain size (from 30 nm to 6 {micro}m) and shows a continuous pattern of behavior. For all materials studied, the strength varied as {lambda}{sup -1}, where {lambda} is the subgrain size. Strengthening from subgrains was found to breakdown at a much smaller subgrain size than strengthening from grains. In addition, the ball-milled materials showed significant strengthening contributions from nano-scale oxide particles. Shear bands are developed during testing of ball-milled materials containing ultra-fine subgrains. A model for shear band development in nano-scale subgrains during deformation has also been developed. The model predicts a strain state of uniaxial compression in the shear band with a strain of -1.24. Subgrains are shown to offer the opportunity for high strength and good work hardening with the absence of yield …
Date: March 23, 2006
Creator: Lesuer, D R; Syn, C K & Sherby, O D
System: The UNT Digital Library
Prediction and observation of tin and silver plasmas with index of refraction greater than one in the soft X-ray range (open access)

Prediction and observation of tin and silver plasmas with index of refraction greater than one in the soft X-ray range

None
Date: March 23, 2006
Creator: Filevich, J.; Grava, J.; Purvis, M.; Marconi, M. C.; Rocca, J. J.; Nilsen, J. et al.
System: The UNT Digital Library
The Sorcerer II Global Ocean Sampling Expedition: Expanding the Universe of Protein Families (open access)

The Sorcerer II Global Ocean Sampling Expedition: Expanding the Universe of Protein Families

Metagenomics projects based on shotgun sequencing of populations of micro-organisms yield insight into protein families. We used sequence similarity clustering to explore proteins with a comprehensive dataset consisting of sequences from available databases together with 6.12 million proteins predicted from an assembly of 7.7 million Global Ocean Sampling (GOS) sequences. The GOS dataset covers nearly all known prokaryotic protein families. A total of 3,995 medium- and large-sized clusters consisting of only GOS sequences are identified, out of which 1,700 have no detectable homology to known families. The GOS-only clusters contain a higher than expected proportion of sequences of viral origin, thus reflecting a poor sampling of viral diversity until now. Protein domain distributions in the GOS dataset and current protein databases show distinct biases. Several protein domains that were previously categorized as kingdom specific are shown to have GOS examples in other kingdoms. About 6,000 sequences (ORFans) from the literature that heretofore lacked similarity to known proteins have matches in the GOS data. The GOS dataset is also used to improve remote homology detection. Overall, besides nearly doubling the number of current proteins, the predicted GOS proteins also add a great deal of diversity to known protein families and shed …
Date: March 23, 2006
Creator: Yooseph, Shibu; Sutton, Granger; Rusch, Douglas B.; Halpern, Aaron L.; Williamson, Shannon J.; Remington, Karin et al.
System: The UNT Digital Library
Stark Tuning of Donor Electron Spins of Silicon (open access)

Stark Tuning of Donor Electron Spins of Silicon

We report Stark shift measurements for {sup 121}Sb donor electron spins in silicon using pulsed electron spin resonance. Interdigitated metal gates on top of a Sb-implanted {sup 28}Si epi-layer are used to apply electric fields. Two Stark effects are resolved: a decrease of the hyperfine coupling between electron and nuclear spins of the donor and a decrease in electron Zeeman g-factor. The hyperfine term prevails at X-band magnetic fields of 0.35T, while the g-factor term is expected to dominate at higher magnetic fields. A significant linear Stark effect is also resolved presumably arising from strain.
Date: March 23, 2006
Creator: Bradbury, Forrest R.; Tyryshkin, Alexei M.; Sabouret, Guillaume; Bokor, Jeff; Schenkel, Thomas & Lyon, Stephen A.
System: The UNT Digital Library
ALE3D Simulation and Measurement of Violence in a Fast Cookoff Experiment for LX-10 (open access)

ALE3D Simulation and Measurement of Violence in a Fast Cookoff Experiment for LX-10

Fast cookoff is of interest in the areas of fire hazard reduction and the development of directed energy systems for defense. During a fast cookoff (thermal explosion), high heat fluxes cause rapid temperature increases and ignition in thin boundary layers. We are developing ALE3D models to describe the thermal, chemical, and mechanical behavior during the heating, ignition, and explosive phases. The candidate models and numerical strategies are being evaluated using benchmark cookoff experiments. Fast cookoff measurements were made in a Scaled-Thermal-Explosion-eXperiment (STEX) for LX-10 (94.7% HMX, 5.3% Viton A) confined in a 4130 steel tube with reinforced end caps. Gaps were present at the side and top of the explosive charge to allow for thermal expansion. The explosive was heated until explosion using radiant heaters. Temperatures were measured using thermocouples positioned on the tube wall and in the explosive. During the explosion, the tube expansion and fragment velocities were measured with strain gauges, Photonic-Doppler-Velocimeters (PDVs), and micropower radar units. A fragment size distribution was constructed from fragments captured in Lexan panels. ALE3D models for chemical, thermal, and mechanical behavior were developed for the heating and explosive processes. A multi-step chemical kinetics model is employed for the HMX while a one-step …
Date: May 23, 2006
Creator: McClelland, M. A.; Maienschein, J. L.; Howard, W. M. & Dehaven, M. R.
System: The UNT Digital Library
Characterization of NIR InGaAs imager arrays for the JDEM SNAPmission concept (open access)

Characterization of NIR InGaAs imager arrays for the JDEM SNAPmission concept

We present the results of a study of the performance of InGaAs detectors conducted for the SuperNova Acceleration Probe (SNAP) dark energy mission concept. Low temperature data from a nominal 1.7um cut-off wavelength 1kx1k InGaAs photodiode array, hybridized to a Rockwell H1RG multiplexer suggest that InGaAs detector performance is comparable to those of existing 1.7um cut-off HgCdTe arrays. Advances in 1.7um HgCdTe dark current and noise initiated by the SNAP detector research and development program makes it the baseline detector technology for SNAP. However, the results presented herein suggest that existing InGaAs technology is a suitable alternative for other future astronomy applications.
Date: May 23, 2006
Creator: Seshadri, S.; Cole, M. D.; Hancock, B.; Ringold, P.; Wrigley, C.; Bonati, M. et al.
System: The UNT Digital Library