States

Enhanced optical absorption due to symmetry breaking in TiO_{2(1-x)} S_{2x} alloys (open access)

Enhanced optical absorption due to symmetry breaking in TiO_{2(1-x)} S_{2x} alloys

None
Date: October 19, 2012
Creator: Schleife, A; Rinke, P; Bechstedt, F & de Walle, C
Object Type: Article
System: The UNT Digital Library
Evaluation Of The Integrated Solubility Model, A Graded Approach For Predicting Phase Distribution In Hanford Tank Waste (open access)

Evaluation Of The Integrated Solubility Model, A Graded Approach For Predicting Phase Distribution In Hanford Tank Waste

The mission of the DOE River Protection Project (RPP) is to store, retrieve, treat and dispose of Hanford's tank waste. Waste is retrieved from the underground tanks and delivered to the Waste Treatment and Immobilization Plant (WTP). Waste is processed through a pretreatment facility where it is separated into low activity waste (LAW), which is primarily liquid, and high level waste (HLW), which is primarily solid. The LAW and HLW are sent to two different vitrification facilities and glass canisters are then disposed of onsite (for LAW) or shipped off-site (for HLW). The RPP mission is modeled by the Hanford Tank Waste Operations Simulator (HTWOS), a dynamic flowsheet simulator and mass balance model that is used for mission analysis and strategic planning. The integrated solubility model (ISM) was developed to improve the chemistry basis in HTWOS and better predict the outcome of the RPP mission. The ISM uses a graded approach to focus on the components that have the greatest impact to the mission while building the infrastructure for continued future improvement and expansion. Components in the ISM are grouped depending upon their relative solubility and impact to the RPP mission. The solubility of each group of components is characterized …
Date: October 19, 2012
Creator: Pierson, Kayla L.; Belsher, Jeremy D. & Seniow, Kendra R.
Object Type: Article
System: The UNT Digital Library
Fast Pyrolysis Oil Stabilization: An Integrated Catalytic and Membrane Approach for Improved Bio-oils (open access)

Fast Pyrolysis Oil Stabilization: An Integrated Catalytic and Membrane Approach for Improved Bio-oils

This University of Massachusetts, Amherst project, "Fast Pyrolysis Oil Stabilization: An Integrated Catalytic and Membrane Approach for Improved Bio-oils" started on 1st February 2009 and finished on August 31st 2011. The project consisted following tasks: Task 1.0: Char Removal by Membrane Separation Technology The presence of char particles in the bio-oil causes problems in storage and end-use. Currently there is no well-established technology to remove char particles less than 10 micron in size. This study focused on the application of a liquid-phase microfiltration process to remove char particles from bio-oil down to slightly sub-micron levels. Tubular ceramic membranes of nominal pore sizes 0.5 and 0.8 µm were employed to carry out the microfiltration, which was conducted in the cross-flow mode at temperatures ranging from 38 to 45 C and at three different trans-membrane pressures varying from 1 to 3 bars. The results demonstrated the removal of the major quantity of char particles with a significant reduction in overall ash content of the bio-oil. The results clearly showed that the cake formation mechanism of fouling is predominant in this process. Task 2.0 Acid Removal by Membrane Separation Technology The feasibility of removing small organic acids from the aqueous fraction of fast …
Date: October 19, 2012
Creator: \Huber, George W.; Upadhye, Aniruddha A.; Ford, David M.; Bhatia, Surita R. & Badger, Phillip C.
Object Type: Report
System: The UNT Digital Library
Incorporation of NREL Solar Advisor Model Photovoltaic Capabilities with GridLAB-D (open access)

Incorporation of NREL Solar Advisor Model Photovoltaic Capabilities with GridLAB-D

This report provides a summary of the work updating the photovoltaic model inside GridLAB-D. The National Renewable Energy Laboratory Solar Advisor Model (SAM) was utilized as a basis for algorithms and validation of the new implementation. Subsequent testing revealed that the two implementations are nearly identical in both solar impacts and power output levels. This synergized model aides the system-level impact studies of GridLAB-D, but also allows more specific details of a particular site to be explored via the SAM software.
Date: October 19, 2012
Creator: Tuffner, Francis K.; Hammerstrom, Janelle L. & Singh, Ruchi
Object Type: Report
System: The UNT Digital Library
Quantitative Tools for Dissection of Hydrogen-Producing Metabolic Networks-Final Report (open access)

Quantitative Tools for Dissection of Hydrogen-Producing Metabolic Networks-Final Report

During this project we have pioneered the development of integrated experimental-computational technologies for the quantitative dissection of metabolism in hydrogen and biofuel producing microorganisms (i.e. C. acetobutylicum and various cyanobacteria species). The application of these new methodologies resulted in many significant advances in the understanding of the metabolic networks and metabolism of these organisms, and has provided new strategies to enhance their hydrogen or biofuel producing capabilities. As an example, using mass spectrometry, isotope tracers, and quantitative flux-modeling we mapped the metabolic network structure in C. acetobutylicum. This resulted in a comprehensive and quantitative understanding of central carbon metabolism that could not have been obtained using genomic data alone. We discovered that biofuel production in this bacterium, which only occurs during stationary phase, requires a global remodeling of central metabolism (involving large changes in metabolite concentrations and fluxes) that has the effect of redirecting resources (carbon and reducing power) from biomass production into solvent production. This new holistic, quantitative understanding of metabolism is now being used as the basis for metabolic engineering strategies to improve solvent production in this bacterium. In another example, making use of newly developed technologies for monitoring hydrogen and NAD(P)H levels in vivo, we dissected the …
Date: October 19, 2012
Creator: Rabinowitz, Joshua D.; Dismukes, G.Charles.; Rabitz, Herschel A. & Amador-Noguez, Daniel
Object Type: Report
System: The UNT Digital Library
Radioactive Waste Conditioning, Immobilisation, And Encapsulation Processes And Technologies: Overview And Advances (Chapter 7) (open access)

Radioactive Waste Conditioning, Immobilisation, And Encapsulation Processes And Technologies: Overview And Advances (Chapter 7)

The main immobilization technologies that are available commercially and have been demonstrated to be viable are cementation, bituminization, and vitrification. Vitrification is currently the most widely used technology for the treatment of high level radioactive wastes (HLW) throughout the world. Most of the nations that have generated HLW are immobilizing in either alkali borosilicate glass or alkali aluminophosphate glass. The exact compositions of nuclear waste glasses are tailored for easy preparation and melting, avoidance of glass-in-glass phase separation, avoidance of uncontrolled crystallization, and acceptable chemical durability, e.g., leach resistance. Glass has also been used to stabilize a variety of low level wastes (LLW) and mixed (radioactive and hazardous) low level wastes (MLLW) from other sources such as fuel rod cladding/decladding processes, chemical separations, radioactive sources, radioactive mill tailings, contaminated soils, medical research applications, and other commercial processes. The sources of radioactive waste generation are captured in other chapters in this book regarding the individual practices in various countries (legacy wastes, currently generated wastes, and future waste generation). Future waste generation is primarily driven by interest in sources of clean energy and this has led to an increased interest in advanced nuclear power production. The development of advanced wasteforms is a …
Date: October 19, 2012
Creator: Jantzen, Carol M.; Lee, William E. & Ojovan, Michael I.
Object Type: Book
System: The UNT Digital Library
Determination of 235U/238U Ratio on Urine by ICP-MS (open access)

Determination of 235U/238U Ratio on Urine by ICP-MS

LLNL Internal Dosimetry Program - The new procedure satisfies the requirement to determine {sup 235}U/{sup 238}U ratio in bioassay urine samples. MDA - The L{sub C} and MDA{sub 95} for {sup 235}U are well below the required detection limit of 0.00035 {mu}g/L. Turn around time - Analysis of 10 samples plus 2 QCs can be completed in one work day (8 hours).
Date: October 19, 2011
Creator: Collins, L.; Gobaleza, A.; Langston, R.; Radev, R.; Than, C.; Wong, C. et al.
Object Type: Article
System: The UNT Digital Library
Energy Efficient Removal of Volatile Organic Compounds (VOCs) and Organic Hazardous Air Pollutants (o-HAPs) from Industrial Waste Streams by Direct Electron Oxidation (open access)

Energy Efficient Removal of Volatile Organic Compounds (VOCs) and Organic Hazardous Air Pollutants (o-HAPs) from Industrial Waste Streams by Direct Electron Oxidation

This research program investigated and quantified the capability of direct electron beam destruction of volatile organic compounds and organic hazardous air pollutants in model industrial waste streams and calculated the energy savings that would be realized by the widespread adoption of the technology over traditional pollution control methods. Specifically, this research determined the quantity of electron beam dose required to remove 19 of the most important non-halogenated air pollutants from waste streams and constructed a technical and economic model for the implementation of the technology in key industries including petroleum refining, organic & solvent chemical production, food & beverage production, and forest & paper products manufacturing. Energy savings of 75 - 90% and green house gas reductions of 66 - 95% were calculated for the target market segments.
Date: October 19, 2011
Creator: Testoni, A. L.
Object Type: Report
System: The UNT Digital Library
Hohlraum Designs for High Velocity Implosions on NIF (open access)

Hohlraum Designs for High Velocity Implosions on NIF

In this paper, we compare experimental shock and capsule trajectories to design calculations using the radiation-hydrodynamics code HYDRA. The measured trajectories from surrogate ignition targets are consistent with reducing the x-ray flux on the capsule by about 85%. A new method of extracting the radiation temperature as seen by the capsule from x-ray intensity and image data shows that about half of the apparent 15% flux deficit in the data with respect to the simulations can be explained by HYDRA overestimating the x-ray flux on the capsule. The National Ignition Campaign (NIC) point-design target is designed to reach a peak fuel-layer velocity of 370 km/s by ablating 90% of its plastic (CH) ablator. The 192-beam National Ignition Facility laser drives a gold hohlraum to a radiation temperature (T{sub RAD}) of 300 eV with a 20 ns-long, 420 TW, 1.3 MJ laser pulse. The hohlraum x-rays couple to the CH ablator in order to apply the required pressure to the outside of the capsule. In this paper, we compare experimental measurements of the hohlraum T{sub RAD} and the implosion trajectory with design calculations using the code hydra. The measured radial positions of the leading shock wave and the unablated shell are …
Date: October 19, 2011
Creator: Meezan, N. B.; Hicks, D. G.; Callahan, D. A.; Olson, R. E.; Schneider, M. S.; Thomas, C. A. et al.
Object Type: Article
System: The UNT Digital Library
Oximes as Inhibitors of Acetylcholinesterase: A Structure Activity Relationship Study (open access)

Oximes as Inhibitors of Acetylcholinesterase: A Structure Activity Relationship Study

None
Date: October 19, 2011
Creator: Sepsova, V.; Karasova, J.; Zemek, F.; Bennion, B. & Kuca, K.
Object Type: Article
System: The UNT Digital Library
POTENTIAL BENCHMARKS FOR ACTINIDE PRODUCTION IN HANFORD REACTORS (open access)

POTENTIAL BENCHMARKS FOR ACTINIDE PRODUCTION IN HANFORD REACTORS

A significant experimental program was conducted in the early Hanford reactors to understand the reactor production of actinides. These experiments were conducted with sufficient rigor, in some cases, to provide useful information that can be utilized today in development of benchmark experiments that may be used for the validation of present computer codes for the production of these actinides in low enriched uranium fuel.
Date: October 19, 2011
Creator: RJ, PUIGH & H, TOFFER
Object Type: Report
System: The UNT Digital Library
Requirements for Defining Utility Drive Cycles: An Exploratory Analysis of Grid Frequency Regulation Data for Establishing Battery Performance Testing Standards (open access)

Requirements for Defining Utility Drive Cycles: An Exploratory Analysis of Grid Frequency Regulation Data for Establishing Battery Performance Testing Standards

Battery testing procedures are important for understanding battery performance, including degradation over the life of the battery. Standards are important to provide clear rules and uniformity to an industry. The work described in this report addresses the need for standard battery testing procedures that reflect real-world applications of energy storage systems to provide regulation services to grid operators. This work was motivated by the need to develop Vehicle-to-Grid (V2G) testing procedures, or V2G drive cycles. Likewise, the stationary energy storage community is equally interested in standardized testing protocols that reflect real-world grid applications for providing regulation services. As the first of several steps toward standardizing battery testing cycles, this work focused on a statistical analysis of frequency regulation signals from the Pennsylvania-New Jersey-Maryland Interconnect with the goal to identify patterns in the regulation signal that would be representative of the entire signal as a typical regulation data set. Results from an extensive time-series analysis are discussed, and the results are explained from both the statistical and the battery-testing perspectives. The results then are interpreted in the context of defining a small set of V2G drive cycles for standardization, offering some recommendations for the next steps toward standardizing testing protocols.
Date: October 19, 2011
Creator: Hafen, Ryan P.; Vishwanathan, Vilanyur V.; Subbarao, Krishnappa & Kintner-Meyer, Michael CW
Object Type: Report
System: The UNT Digital Library
Understanding Bulk Power Reliability: The Importance of Good Data and A Critical Review of Existing Sources (open access)

Understanding Bulk Power Reliability: The Importance of Good Data and A Critical Review of Existing Sources

Bulk power system reliability is of critical importance to the electricity sector. Complete and accurate information on events affecting the bulk power system is essential for assessing trends and efforts to maintain or improve reliability. Yet, current sources of this information were not designed with these uses in mind. They were designed, instead, to support real-time emergency notification to industry and government first-responders. This paper reviews information currently collected by both industry and government sources for this purpose and assesses factors that might affect their usefulness in supporting the academic literature that has relied upon them to draw conclusions about the reliability of the US electric power system.
Date: October 19, 2011
Creator: Fisher, Emily; Eto, Joseph H. & LaCommare, Kristina Hamachi
Object Type: Article
System: The UNT Digital Library
Annual report of groundwater monitoring at Centralia, Kansas, in 2009. (open access)

Annual report of groundwater monitoring at Centralia, Kansas, in 2009.

In September 2005, periodic sampling of groundwater was initiated by the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) in the vicinity of a grain storage facility formerly operated by the CCC/USDA at Centralia, Kansas. The sampling at Centralia is being performed on behalf of the CCC/USDA by Argonne National Laboratory, in accord with a monitoring program approved by the Kansas Department of Health and Environment (KDHE). The objective is to monitor levels of carbon tetrachloride contamination identified in the groundwater at Centralia (Argonne 2003, 2004, 2005a). Under the KDHE-approved monitoring plan (Argonne 2005b), the groundwater was sampled twice yearly from September 2005 until September 2007 for analyses for volatile organic compounds (VOCs), as well as measurement of selected geochemical parameters to aid in the evaluation of possible natural contaminant degradation (reductive dechlorination) processes in the subsurface environment. The results from the two-year sampling program demonstrated the presence of carbon tetrachloride contamination at levels exceeding the KDHE Tier 2 risk-based screening level (RBSL) of 5 {micro}g/L for this compound in a localized groundwater plume that has shown little movement. The relative concentrations of chloroform, the primary degradation product of carbon tetrachloride, suggested that some degree of reductive dechlorination …
Date: October 19, 2010
Creator: LaFreniere, L. M.
Object Type: Report
System: The UNT Digital Library
Measurements of the Ion Species of Cathodic Arc Plasma in an Axial Magnetic Field (open access)

Measurements of the Ion Species of Cathodic Arc Plasma in an Axial Magnetic Field

Metal and gas ion species and their charge state distributions were measured for pulsed copper cathodic arcs in argon background gas in the presence of an axial magnetic field. It was found that changing the cathode position relative to anode and ion extraction system as well as increasing the gas pressure did not much affect the arc burning voltage and the related power dissipation. However, the burning voltage and power dissipation greatly increased as the magnetic field strength was increased. The fraction of metal ions and the mean ion charge state were reduced as the discharge length was increased. The observations can be explained by the combination of charge exchange collisions and electron impact ionization. They confirm that previously published data on characteristic material-dependent charge state distributions (e.g., Anders and Yushkov, J. Appl. Phys., Vol. 91, pp. 4824-4832, 2002) are not universal but valid for high vacuum conditions and the specifics of the applied magnetic fields.
Date: October 19, 2010
Creator: Oks, Efim & Anders, Andre
Object Type: Article
System: The UNT Digital Library
Microtomography and pore-scale modeling of two-phase Fluid Distribution (open access)

Microtomography and pore-scale modeling of two-phase Fluid Distribution

Synchrotron-based X-ray microtomography (micro CT) at the Advanced Light Source (ALS) line 8.3.2 at the Lawrence Berkeley National Laboratory produces three-dimensional micron-scale-resolution digital images of the pore space of the reservoir rock along with the spacial distribution of the fluids. Pore-scale visualization of carbon dioxide flooding experiments performed at a reservoir pressure demonstrates that the injected gas fills some pores and pore clusters, and entirely bypasses the others. Using 3D digital images of the pore space as input data, the method of maximal inscribed spheres (MIS) predicts two-phase fluid distribution in capillary equilibrium. Verification against the tomography images shows a good agreement between the computed fluid distribution in the pores and the experimental data. The model-predicted capillary pressure curves and tomography-based porosimetry distributions compared favorably with the mercury injection data. Thus, micro CT in combination with modeling based on the MIS is a viable approach to study the pore-scale mechanisms of CO{sub 2} injection into an aquifer, as well as more general multi-phase flows.
Date: October 19, 2010
Creator: Silin, D.; Tomutsa, L.; Benson, S. & Patzek, T.
Object Type: Article
System: The UNT Digital Library
NEXT GENERATION MELTER OPTIONEERING STUDY - INTERIM REPORT (open access)

NEXT GENERATION MELTER OPTIONEERING STUDY - INTERIM REPORT

The next generation melter (NOM) development program includes a down selection process to aid in determining the recommended vitrification technology to implement into the WTP at the first melter change-out which is scheduled for 2025. This optioneering study presents a structured value engineering process to establish and assess evaluation criteria that will be incorporated into the down selection process. This process establishes an evaluation framework that will be used progressively throughout the NGM program, and as such this interim report will be updated on a regular basis. The workshop objectives were achieved. In particular: (1) Consensus was reached with stakeholders and technology providers represented at the workshop regarding the need for a decision making process and the application of the D{sub 2}0 process to NGM option evaluation. (2) A framework was established for applying the decision making process to technology development and evaluation between 2010 and 2013. (3) The criteria for the initial evaluation in 2011 were refined and agreed with stakeholders and technology providers. (4) The technology providers have the guidance required to produce data/information to support the next phase of the evaluation process. In some cases it may be necessary to reflect the data/information requirements and overall approach …
Date: October 19, 2010
Creator: MF, GRAY; RB, CALMUS; G, RAMSEY; J, LOMAX & H, ALLEN
Object Type: Report
System: The UNT Digital Library
Use of the ARM Measurement of Spectral Zenith Radiance For Better Understanding Of 3D Cloud-Radiation Processes and Aerosol-Cloud Interaction (open access)

Use of the ARM Measurement of Spectral Zenith Radiance For Better Understanding Of 3D Cloud-Radiation Processes and Aerosol-Cloud Interaction

Our proposal focuses on cloud-radiation processes in a general 3D cloud situation, with particular emphasis on cloud optical depth and effective particle size. We also focus on zenith radiance measurements, both active and passive. The proposal has three main parts. Part One exploits the “solar-background” mode of ARM lidars to allow them to retrieve cloud optical depth not just for thin clouds but for all clouds. This also enables the study of aerosol cloud interactions with a single instrument. Part Two exploits the large number of new wavelengths offered by ARM’s zenith-pointing ShortWave Spectrometer (SWS), especially during CLASIC, to develop better retrievals not only of cloud optical depth but also of cloud particle size. We also propose to take advantage of the SWS’ 1 Hz sampling to study the “twilight zone” around clouds where strong aerosol-cloud interactions are taking place. Part Three involves continuing our cloud optical depth and cloud fraction retrieval research with ARM’s 2NFOV instrument by, first, analyzing its data from the AMF-COPS/CLOWD deployment, and second, making our algorithms part of ARM’s operational data processing.
Date: October 19, 2010
Creator: Chiu, D. Jui-Yuan
Object Type: Report
System: The UNT Digital Library

2009 NGSI Safeguards Courses at DOE National Laboratories

PowerPoint Presentation
Date: October 19, 2009
Creator: Rosenthal, M. D.; Fishbone, L.; Kirk, B.; Boyer, B.; Doyle, J.; Meek, E. et al.
Object Type: Presentation
System: The UNT Digital Library
Assembly and Loading of LQS01, a Shell-Based 3.7 m Long Nb3Sn Quadrupole Magnet for LARP (open access)

Assembly and Loading of LQS01, a Shell-Based 3.7 m Long Nb3Sn Quadrupole Magnet for LARP

The LHC Accelerator Research Program (LARP) has been engaged in the fabrication of the 3.7 m long quadrupole magnet LQS01 in order to demonstrate that Nb{sub 3}Sn magnets are a viable option for future LHC Luminosity upgrades. The LQS01 design, a scale-up of the 1 m long Technology Quadrupole TQS, includes four 3.4 m long cos(theta) coils contained in a support structure based on four 1 m long aluminum shells pre-tensioned with water-pressurized bladders (shell-type structure). In order to verify assembly procedures and loading operations, the structure was pre-stressed around solid aluminum 'dummy coils' and cooled-down to 77 K. Mechanical behavior and stress variations were monitored with strain gauges mounted on the structure and on the dummy coils. The dummy coils were then replaced with Nb{sub 3}Sn coils in a second assembly and loading procedure, in preparation for the cool-down and test. This paper reports on the cool-down test with dummy coils and on the assembly and loading of LQS01, with a comparison between 3D finite element model predictions and strain gauge data.
Date: October 19, 2009
Creator: Ferracin, P.; Ambrosio, G.; Anerella, M.; Bingham, B.; Bossert, R.; Caspi, S. et al.
Object Type: Article
System: The UNT Digital Library
Design of a High Field Nb3Al Common Coil Magnet (open access)

Design of a High Field Nb3Al Common Coil Magnet

A high field Nb{sub 3}Al common coil magnet is under development as an R&D of 'Advanced Superconducting Magnets for the LHC Luminosity Upgrade', in the framework of the CERN-KEK cooperation program. The goal of this research is to demonstrate the feasibility of high field magnet wound with Nb{sub 3}Al cable. The common coil approach and the shell-based structure were adopted in the design of this magnet. Besides three Nb{sub 3}Al coils, two Nb{sub 3}Sn coils were included to increase the peak field of the whole magnet. The two types of coils were designed with different straight lengths to reduce the peak field of the Nb{sub 3}Sn coils. The peak fields of the Nb{sub 3}Al and Nb{sub 3}Sn coils are 13.1 T and 11.8 T respectively. An aluminum shell together with four aluminum rods applies stress to the coils to overcome the Lorenz force during excitation. Two different support structures for the superconducting coils were introduced in this paper. The development status is also presented.
Date: October 19, 2009
Creator: Xu, Qingjin; Sasaki, Kenichi; Nakamoto, Tatsushi; Terashima, Akio; Tsuchiya, Kiyosumi; Yamamoto, Akira et al.
Object Type: Article
System: The UNT Digital Library
Ferrimagnetic ordering of single crystal Fe1-xGax thin films (open access)

Ferrimagnetic ordering of single crystal Fe1-xGax thin films

Molecular beam epitaxy was used to deposit body centered cubic single crystal Fe{sub 1-x}Ga{sub x} thin films on MgO(001) and ZnSe/GaAs(001) substrates well beyond the bulk stability concentration of about 28%. The crystal quality of the substrate surface and each deposited layer was monitored in situ by reflection high energy electron diffraction. The magnetization of the samples as a function of Ga is found to decrease more rapidly than a simple dilution effect, and element-specific x-ray magnetic circular dichroism ascribes this trend to a decrease in the Fe moment and an induced moment in the Ga that is antialigned to the Fe moment.
Date: October 19, 2009
Creator: McClure, A.; Arenholz, E. & Idzerda, Y. U.
Object Type: Article
System: The UNT Digital Library
Imaging the molecular dynamics of dissociative electron attachment to water (open access)

Imaging the molecular dynamics of dissociative electron attachment to water

Momentum imaging experiments on dissociative electron attachment to the water molecule are combined with ab initio theoretical calculations of the angular dependence of the quantum mechanical amplitude for electron attachment to provide a detailed picture of the molecular dynamics of dissociation attachment via the two lowest energy Feshbach resonances. The combination of momentum imaging experiments and theory can reveal dissociation dynamics for which the axial recoil approximation breaks down and thus provides a powerful reaction microscope for DEA to polyatomics.
Date: October 19, 2009
Creator: Adaniya, Hidihito; Rudek, B.; Osipov, Timur; Haxton, Dan; Weber, Thorsten; Rescigno, Thomas N. et al.
Object Type: Article
System: The UNT Digital Library
Internal electric-field-lines distribution in CdZnTe detectors measured using X-ray mapping (open access)

Internal electric-field-lines distribution in CdZnTe detectors measured using X-ray mapping

The ideal operation of CdZnTe devices entails having a uniformly distributed internal electric field. Such uniformity especially is critical for thick long-drift-length detectors, such as large-volume CPG and 3-D multi-pixel devices. Using a high-spatial resolution X-ray mapping technique, we investigated the distribution of the electric field in real devices. Our measurements demonstrate that in thin detectors, <5 mm, the electric field-lines tend to bend away from the side surfaces (i.e., a focusing effect). In thick detectors, >1 cm, with a large aspect ratio (thickness-to-width ratio), we observed two effects: the electric field lines bending away from or towards the side surfaces, which we called, respectively, the focusing field-line distribution and the defocusing field-line distribution. In addition to these large-scale variations, the field-line distributions were locally perturbed by the presence of extended defects and residual strains existing inside the crystals. We present our data clearly demonstrating the non-uniformity of the internal electric field.
Date: October 19, 2009
Creator: Bolotnikov, A. E.; Camarda, G. S.; Cui, Y.; Hossain, A.; Yang, G.; Yao, H. W. et al.
Object Type: Article
System: The UNT Digital Library