Absolute Bunch Length Measurements by Incoherent Radiation Fluctuation Analysis (open access)

Absolute Bunch Length Measurements by Incoherent Radiation Fluctuation Analysis

By analyzing the pulse to pulse intensity fluctuations of the radiation emitted by a charge particle in the incoherent part of the spectrum, it is possible to extract information about the spatial distribution of the beam. At the Advanced Light Source (ALS) of the Lawrence Berkeley National Laboratory, we have developed and successfully tested a simple scheme based on this principle that allows for the absolute measurement of the rms bunch length. A description of the method and the experimental results are presented.
Date: December 9, 2009
Creator: Sannibale, F.; /LBL, Berkeley; Stupakov, G.V.; /SLAC; Zolotorev, M.S.; /LBL, Berkeley et al.
Object Type: Article
System: The UNT Digital Library
ACCURATE TEMPERATURE MEASUREMENTS IN A NATURALLY-ASPIRATED RADIATION SHIELD (open access)

ACCURATE TEMPERATURE MEASUREMENTS IN A NATURALLY-ASPIRATED RADIATION SHIELD

Experiments and calculations were conducted with a 0.13 mm fine wire thermocouple within a naturally-aspirated Gill radiation shield to assess and improve the accuracy of air temperature measurements without the use of mechanical aspiration, wind speed or radiation measurements. It was found that this thermocouple measured the air temperature with root-mean-square errors of 0.35 K within the Gill shield without correction. A linear temperature correction was evaluated based on the difference between the interior plate and thermocouple temperatures. This correction was found to be relatively insensitive to shield design and yielded an error of 0.16 K for combined day and night observations. The correction was reliable in the daytime when the wind speed usually exceeds 1 m s{sup -1} but occasionally performed poorly at night during very light winds. Inspection of the standard deviation in the thermocouple wire temperature identified these periods but did not unambiguously locate the most serious events. However, estimates of sensor accuracy during these periods is complicated by the much larger sampling volume of the mechanically-aspirated sensor compared with the naturally-aspirated sensor and the presence of significant near surface temperature gradients. The root-mean-square errors therefore are upper limits to the aspiration error since they include intrinsic …
Date: September 9, 2009
Creator: Kurzeja, R.
Object Type: Article
System: The UNT Digital Library
ACRF Instrumentation Status and Information August 2009 (open access)

ACRF Instrumentation Status and Information August 2009

The purpose of this report is to provide a concise but comprehensive overview of Atmospheric Radiation Measurement Climate Research Facility instrumentation status. The report is divided into the following five sections: (1) new instrumentation in the process of being acquired and deployed, (2) field campaigns, (3) existing instrumentation and progress on improvements or upgrades, (4) proposed future instrumentation, and (5) Small Business Innovation Research instrument development.
Date: September 9, 2009
Creator: Voyles, J. W.
Object Type: Report
System: The UNT Digital Library
ALUMINUM HYDRIDE: A REVERSIBLE MATERIAL FOR HYDROGEN STORAGE (open access)

ALUMINUM HYDRIDE: A REVERSIBLE MATERIAL FOR HYDROGEN STORAGE

Hydrogen storage is one of the challenges to be overcome for implementing the ever sought hydrogen economy. Here we report a novel cycle to reversibly form high density hydrogen storage materials such as aluminium hydride. Aluminium hydride (AlH{sub 3}, alane) has a hydrogen storage capacity of 10.1 wt% H{sub 2}, 149 kg H{sub 2}/m{sup 3} volumetric density and can be discharged at low temperatures (< 100 C). However, alane has been precluded from use in hydrogen storage systems because of the lack of practical regeneration methods. The direct hydrogenation of aluminium to form AlH{sub 3} requires over 10{sup 5} bars of hydrogen pressure at room temperature and there are no cost effective synthetic means. Here we show an unprecedented reversible cycle to form alane electrochemically, using alkali metal alanates (e.g. NaAlH{sub 4}, LiAlH{sub 4}) in aprotic solvents. To complete the cycle, the starting alanates can be regenerated by direct hydrogenation of the dehydrided alane and the alkali hydride being the other compound formed in the electrochemical cell. The process of forming NaAlH{sub 4} from NaH and Al is well established in both solid state and solution reactions. The use of adducting Lewis bases is an essential part of this cycle, …
Date: January 9, 2009
Creator: Zidan, R; Christopher Fewox, C; Brenda Garcia-Diaz, B & Joshua Gray, J
Object Type: Article
System: The UNT Digital Library
ALUMINUM HYDRIDE: A REVERSIBLE STORAGE MATERIAL FOR HYDROGEN STORAGE (open access)

ALUMINUM HYDRIDE: A REVERSIBLE STORAGE MATERIAL FOR HYDROGEN STORAGE

One of the challenges of implementing the hydrogen economy is finding a suitable solid H{sub 2} storage material. Aluminium (alane, AlH{sub 3}) hydride has been examined as a potential hydrogen storage material because of its high weight capacity, low discharge temperature, and volumetric density. Recycling the dehydride material has however precluded AlH{sub 3} from being implemented due to the large pressures required (>10{sup 5} bar H{sub 2} at 25 C) and the thermodynamic expense of chemical synthesis. A reversible cycle to form alane electrochemically using NaAlH{sub 4} in THF been successfully demonstrated. Alane is isolated as the triethylamine (TEA) adduct and converted to unsolvated alane by heating under vacuum. To complete the cycle, the starting alanate can be regenerated by direct hydrogenation of the dehydrided alane and the alkali hydride (NaH) This novel reversible cycle opens the door for alane to fuel the hydrogen economy.
Date: January 9, 2009
Creator: Zidan, R; Christopher Fewox, C; Brenda Garcia-Diaz, B & Joshua Gray, J
Object Type: Article
System: The UNT Digital Library
Amorphous clusters in Co implanted ZnO induced by boron pre-implantation (open access)

Amorphous clusters in Co implanted ZnO induced by boron pre-implantation

We demonstrate the formation of superparamagnetic/ferromagnetic regions within ZnO(0001) single crystals sequently implanted with B and Co. While the pre-implantation with B plays a minor role for the electrical transport properties, its presence leads to the formation of amorphous phases. Moreover, B acts strongly reducing on the implanted Co. Thus, the origin of the ferromagnetic ordering in local clusters with large Co concentration is itinerant d-electrons as in the case of metallic Co. The metallic amorphous phases are non-detectable by common X-ray diffraction.
Date: February 9, 2009
Creator: Potzger, K.; Shalimov, A.; Zhou, S.; Schmidt, H.; Mucklich, A.; Helm, M. et al.
Object Type: Article
System: The UNT Digital Library
Analysis of In situ Observations of Cloud Microphysics from M-PACE Final Report, DOE Grant Agreement No. DE-FG02-06ER64168 (open access)

Analysis of In situ Observations of Cloud Microphysics from M-PACE Final Report, DOE Grant Agreement No. DE-FG02-06ER64168

This report summarizes the findings and accomplishments of work performed under DOE Grant Agreement No. DE-FG02-06ER64168. The focus of the work was the analysis of in situ observations collected by the University of North Dakota Citation research aircraft during the Mixed-Phase Arctic Cloud Experiment (M-PACE). This project was conducted in 2004 along the North Slope of Alaska. The objectives of the research were: to characterize certain microphysical properties of clouds sampled during M-PACE, including spatial variability, precipitation formation, ice multiplication; to examine instrument performance and certain data processing algorithms; and to collaborate with other M-PACE investigators on case study analyses. A summary of the findings of the first two objectives is given here in parts 1 and 2; full results are contained in reports listed in part 3 of this report. The collaborative efforts are described in the publications listed in part 3.
Date: January 9, 2009
Creator: Poellot, Michael R.
Object Type: Report
System: The UNT Digital Library
Annual Site Environmental Report: 2008 (ASER) (open access)

Annual Site Environmental Report: 2008 (ASER)

This report provides information about environmental programs during the calendar year of 2008 at the SLAC National Accelerator Laboratory (SLAC), Menlo Park, California. Activities that span the calendar year, i.e., stormwater monitoring covering the winter season of 2008/2009 (October 2008 through May 2009), are also included. Production of an annual site environmental report (ASER) is a requirement established by the United States Department of Energy (DOE) for all management and operating (M&O) contractors throughout the DOE complex. SLAC is a federally-funded research and development center with Stanford University as the M&O contractor. Under Executive Order (EO) 13423, Strengthening Federal Environmental, Energy, and Transportation Management, and DOE Order 450.1A, Environmental Protection Program, SLAC effectively implements and integrates the key elements of an Environmental Management System (EMS) to achieve the site's integrated safety and environmental management system goals. For normal daily activities, SLAC managers and supervisors are responsible for ensuring that policies and procedures are understood and followed so that: (1) Worker safety and health are protected; (2) The environment is protected; and (3) Compliance is ensured. Throughout 2008, SLAC continued to improve its management systems. These systems provided a structured framework for SLAC to implement 'greening of the government' initiatives such …
Date: November 9, 2009
Creator: Sabba, D.
Object Type: Report
System: The UNT Digital Library
BAC-FISH assays delineate complex chromosomal rearrangements in a case of post-Chernobyl childhood thyroid cancer (open access)

BAC-FISH assays delineate complex chromosomal rearrangements in a case of post-Chernobyl childhood thyroid cancer

Structural chromosome aberrations are known hallmarks of many solid tumors. In the papillary form of thyroid cancer (PTC), for example, activation of the receptor tyrosine kinase (RTK) genes, RET and neurotrophic tyrosine kinase receptor type I (NTRK1) by intra- and interchromosomal rearrangements has been suggested as a cause of the disease. However, many phenotypically similar tumors do not carry an activated RET or NTRK-1 gene or express abnormal ret or NTRK-1 transcripts. Thus, we hypothesize that other cellular RTK-type genes are aberrantly expressed in these tumors. Using fluorescence in situ hybridization-based methods, we are studying karyotype changes in a relatively rare subgroup of PTCs, i.e., tumors that arose in children following the 1986 nuclear accident in Chernobyl, Ukraine. Here, we report our technical developments and progress in deciphering complex chromosome aberrations in case S48TK, an aggressively growing PTC cell line, which shows an unusual high number of unbalanced translocations.
Date: March 9, 2009
Creator: Kwan, Johnson; Baumgartner, Adolf; Lu, Chun-Mei; Wang, Mei; Weier, Jingly F.; Zitzelsberger, Horst F. et al.
Object Type: Report
System: The UNT Digital Library
Beam Echo Effect for Generation of Short-Wavelength Radiation (open access)

Beam Echo Effect for Generation of Short-Wavelength Radiation

The Echo-Enabled Harmonic Generation (EEHG) FEL uses two modulators in combination with two dispersion sections to generate a high-harmonic density modulation starting with a relatively small initial energy modulation of the beam. After presenting the concept of the EEHG, we address several practically important issues, such as the effect of coherent and incoherent synchrotron radiation in the dispersion sections. Using a representative realistic set of beam parameters, we show how the EEHG scheme enhances the FEL performance and allows one to generate a fully (both longitudinally and transversely) coherent radiation. We then discuss application of the echo modulation for generation of attosecond pulses of radiation, and also using echo for generation of terahertz radiation. We present main parameters of a proof-of-principle experiment currently being planned at SLAC for demonstration of the echo modulation mechanism.
Date: December 9, 2009
Creator: Stupakov, G.
Object Type: Article
System: The UNT Digital Library
BF3 Neutron Detector Tests (open access)

BF3 Neutron Detector Tests

Radiation portal monitors used for interdiction of illicit materials at borders include highly sensitive neutron detection systems. The main reason for having neutron detection capability is to detect fission neutrons from plutonium. The currently deployed radiation portal monitors (RPMs) from Ludlum and Science Applications International Corporation (SAIC) use neutron detectors based upon 3He-filled gas proportional counters, which are the most common large neutron detector. There is a declining supply of 3He in the world; thus, methods to reduce the use of this gas in RPMs with minimal changes to the current system designs and detection capabilities are being investigated. Reported here are the results of tests of the efficiency of BF3 tubes at a pressure of 800 torr. These measurements were made partially to validate models of the RPM system that have been modified to simulate the performance of BF3-filled tubes. While BF3 could be a potential replacement for 3He, there are limitations to its use in deployed systems.
Date: December 9, 2009
Creator: Kouzes, Richard T.; Ely, James H.; Lintereur, Azaree T.; Siciliano, Edward R. & Woodring, Mitchell L.
Object Type: Report
System: The UNT Digital Library
Burnup Calculations for Kipt Accelerator Driven Subcritical Facility Using Monte Carlo Computer Codes-Mcb and Mcnpx. (open access)

Burnup Calculations for Kipt Accelerator Driven Subcritical Facility Using Monte Carlo Computer Codes-Mcb and Mcnpx.

Argonne National Laboratory (ANL) of USA and Kharkov Institute of Physics and Technology (KIPT) of Ukraine have been collaborating on the conceptual design development of an electron accelerator driven subcritical (ADS) facility, using the KIPT electron accelerator. The neutron source of the subcritical assembly is generated from the interaction of 100 KW electron beam with a natural uranium target. The electron beam has a uniform spatial distribution and electron energy in the range of 100 to 200 MeV. The main functions of the subcritical assembly are the production of medical isotopes and the support of the Ukraine nuclear power industry. Neutron physics experiments and material structure analyses are planned using this facility. With the 100 KW electron beam power, the total thermal power of the facility is {approx}375 kW including the fission power of {approx}260 kW. The burnup of the fissile materials and the buildup of fission products reduce continuously the reactivity during the operation, which reduces the neutron flux level and consequently the facility performance. To preserve the neutron flux level during the operation, fuel assemblies should be added after long operating periods to compensate for the lost reactivity. This process requires accurate prediction of the fuel burnup, the …
Date: June 9, 2009
Creator: Gohar, Y.; Zhong, Z. & Talamo, A.
Object Type: Report
System: The UNT Digital Library
Calculation of Coherent Synchrotron Radiation Impedance Using the Mode Expansion Method (open access)

Calculation of Coherent Synchrotron Radiation Impedance Using the Mode Expansion Method

We study an impedance due to coherent synchrotron radiation (CSR) generated by a short bunch of charged particles passing through a dipole magnet of finite length in a vacuum chamber of a given cross section. In our method we decompose the electromagnetic field of the beam over the eigenmodes of the toroidal chamber and derive a system of equations for the expansion coefficients in the series. The general method is further specialized for a toroidal vacuum chamber of a rectangular cross section where the eigenmodes can be computed analytically. We also develop a computer code that calculates the CSR impedance for a toroid of rectangular cross section. Numerical results obtained with the code are presented in the paper.
Date: December 9, 2009
Creator: Stupakov, G. V. & Kotelnikov, I. A.
Object Type: Article
System: The UNT Digital Library
Canada-USA Salmon Shelf Survival Study, 2007-2008 Annual Report. (open access)

Canada-USA Salmon Shelf Survival Study, 2007-2008 Annual Report.

Historically, salmon stocks from the Columbia River and Snake River formed one of the most valuable fisheries on the west coast of North America. However, salmon and steelhead returns sharply declined during the 1980s and 1990s to reach nearly 1 million fish. Although several factors may be responsible for the decline of Columbia River salmon and steelhead, there is increasing evidence that these drastic declines were primarily attributable to persistently unfavorable ocean conditions. Hence, an understanding of the effects of ocean conditions on salmon production is required to forecast the return of salmon to the Columbia River basin and to assess the efficacy of mitigation measures such as flow regulation on salmon resources in this system. The Canadian Program on High Seas Salmon has been collecting juvenile salmon and oceanographic data off the west coast of British Columbia and Southeast Alaska since 1998 to assess the effects of ocean conditions on the distribution, migration, growth, and survival of Pacific salmon. Here, we present a summary of the work conducted as part of the Canada-USA Salmon Shelf Survival Study during the 2008 fiscal year and compare these results with those obtained from previous years. The working hypothesis of this research is …
Date: March 9, 2009
Creator: Trudel, Marc; Tucker, Strahan & Morris, John
Object Type: Report
System: The UNT Digital Library
CEMENTITIOUS BARRIERS MODELING FOR PERFORMANCE ASSESSMENTS OF SHALLOW LAND BURIAL OF LOW LEVEL RADIOACTIVE WASTE - 9243 (open access)

CEMENTITIOUS BARRIERS MODELING FOR PERFORMANCE ASSESSMENTS OF SHALLOW LAND BURIAL OF LOW LEVEL RADIOACTIVE WASTE - 9243

The Cementitious Barriers Partnership (CBP) was created to develop predictive capabilities for the aging of cementitious barriers over long timeframes. The CBP is a multi-agency, multi-national consortium working under a U.S. Department of Energy (DOE) Environmental Management (EM-21) funded Cooperative Research and Development Agreement (CRADA) with the Savannah River National Laboratory (SRNL) as the lead laboratory. Members of the CBP are SRNL, Vanderbilt University, the U.S. Nuclear Regulatory Commission (USNRC), National Institute of Standards and Technology (NIST), SIMCO Technologies, Inc. (Canada), and the Energy Research Centre of the Netherlands (ECN). A first step in developing advanced tools is to determine the current state-of-the-art. A review has been undertaken to assess the treatment of cementitious barriers in Performance Assessments (PA). Representatives of US DOE sites which have PAs for their low level waste disposal facilities were contacted. These sites are the Idaho National Laboratory, Oak Ridge National Laboratory, Los Alamos National Laboratory, Nevada Test Site, and Hanford. Several of the more arid sites did not employ cementitious barriers. Of those sites which do employ cementitious barriers, a wide range of treatment of the barriers in a PA was present. Some sites used conservative, simplistic models that even though conservative still showed …
Date: January 9, 2009
Creator: Taylor, G
Object Type: Article
System: The UNT Digital Library
Characterization, Leaching, and Filtration Testing for Tributyl Phosphate (TBP, Group 7) Actual Waste Sample Composites (open access)

Characterization, Leaching, and Filtration Testing for Tributyl Phosphate (TBP, Group 7) Actual Waste Sample Composites

.A testing program evaluating actual tank waste was developed in response to Task 4 from the M-12 External Flowsheet Review Team (EFRT) issue response plan. The bulk water-insoluble solid wastes that are anticipated to be delivered to the Waste Treatment and Immobilization Plant (WTP) were identified according to type such that the actual waste testing could be targeted to the relevant categories. Eight broad waste groupings were defined. Samples available from the 222S archive were identified and obtained for testing. The actual waste-testing program included homogenizing the samples by group, characterizing the solids and aqueous phases, and performing parametric leaching tests. The tributyl phosphate sludge (TBP, Group 7) is the subject of this report. The Group 7 waste was anticipated to be high in phosphorus as well as aluminum in the form of gibbsite. Both are believed to exist in sufficient quantities in the Group 7 waste to address leaching behavior. Thus, the focus of the Group 7 testing was on the removal of both P and Al. The waste-type definition, archived sample conditions, homogenization activities, characterization (physical, chemical, radioisotope, and crystal habit), and caustic leaching behavior as functions of time, temperature, and hydroxide concentration are discussed in this report. …
Date: March 9, 2009
Creator: Edwards, Matthew K.; Billing, Justin M.; Blanchard, David L.; Buck, Edgar C.; Casella, Amanda J.; Casella, Andrew M. et al.
Object Type: Report
System: The UNT Digital Library
Characterization of Filtration Scale-Up Performance (open access)

Characterization of Filtration Scale-Up Performance

The scale-up performance of sintered stainless steel crossflow filter elements planned for use at the Pretreatment Engineering Platform (PEP) and at the Waste Treatment and Immobilization Plant (WTP) were characterized in partial fulfillment (see Table S.1) of the requirements of Test Plan TP RPP WTP 509. This test report details the results of experimental activities related only to filter scale-up characterization. These tests were performed under the Simulant Testing Program supporting Phase 1 of the demonstration of the pretreatment leaching processes at PEP. Pacific Northwest National Laboratory (PNNL) conducted the tests discussed herein for Bechtel National, Inc. (BNI) to address the data needs of Test Specification 24590-WTP-TSP-RT-07-004. Scale-up characterization tests employ high-level waste (HLW) simulants developed under the Test Plan TP-RPP-WTP-469. The experimental activities outlined in TP-RPP-WTP-509 examined specific processes from two broad areas of simulant behavior: 1) leaching performance of the boehmite simulant as a function of suspending phase chemistry and 2) filtration performance of the blended simulant with respect to filter scale-up and fouling. With regard to leaching behavior, the effect of anions on the kinetics of boehmite leaching was examined. Two experiments were conducted: 1) one examined the effect of the aluminate anion on the rate of …
Date: March 9, 2009
Creator: Daniel, Richard C.; Billing, Justin M.; Luna, Maria L.; Cantrell, Kirk J.; Peterson, Reid A.; Bonebrake, Michael L. et al.
Object Type: Report
System: The UNT Digital Library
Coherent rho 0 photoproduction in bulk matter at high energies (open access)

Coherent rho 0 photoproduction in bulk matter at high energies

The momentum transfer {Delta}k required for a photon to scatter from a target and emerge as a {rho}{sup 0} decreases as the photon energy k rises. For k > 3 x 10{sup 14} eV, {Delta}k is small enough that the interaction cannot be localized to a single nucleus. At still higher energies, photons may coherently scatter elastically from bulk matter and emerge as a {rho}{sup 0}, in a manner akin to kaon regeneration. Constructive interference from the different nuclei coherently raises the cross section and the interaction probability rises linearly with energy. At energies above 10{sup 23} eV, coherent conversion is the dominant process; photons interact predominantly as {rho}{sup 0}. We compute the coherent scattering probabilities in slabs of lead, water and rock, and discuss the implications of the increased hadronic interaction probabilities for photons on ultra-high energy shower development.
Date: January 9, 2009
Creator: Couderc, Elsa & Klein, Spencer
Object Type: Article
System: The UNT Digital Library
CTUIR Umatilla Anadromous Fisheries Habitat Project : A Columbia River Basin Fish Habitat Project 2008 Annual Report. (open access)

CTUIR Umatilla Anadromous Fisheries Habitat Project : A Columbia River Basin Fish Habitat Project 2008 Annual Report.

The Umatilla Anadromous Fisheries Habitat Project (UAFHP) is an ongoing effort to protect, enhance, and restore riparian and instream habitat for the natural production of anadromous salmonids in the Umatilla River Basin, Northeast Oregon. Flow quantity, water temperature, passage, and lack of in-stream channel complexity have been identified as the key limiting factors in the basin. During the 2008 Fiscal Year (FY) reporting period (February 1, 2008-January 31, 2009) primary project activities focused on improving instream and riparian habitat complexity, migrational passage, and restoring natural channel morphology and floodplain function. Eight primary fisheries habitat enhancement projects were implemented on Meacham Creek, Birch Creek, West Birch Creek, McKay Creek, West Fork Spring Hollow, and the Umatilla River. Specific restoration actions included: (1) rectifying one fish passage barrier on West Birch Creek; (2) participating in six projects planting 10,000 trees and seeding 3225 pounds of native grasses; (3) donating 1000 ft of fencing and 1208 fence posts and associated hardware for 3.6 miles of livestock exclusion fencing projects in riparian areas of West Birch and Meacham Creek, and for tree screens to protect against beaver damage on West Fork Spring Hollow Creek; (4) using biological control (insects) to reduce noxious weeds on …
Date: February 9, 2009
Creator: Hoverson, Eric D. & Amonette, Alexandra
Object Type: Report
System: The UNT Digital Library
DARHT 2 kA Cathode Development (open access)

DARHT 2 kA Cathode Development

In the campaign to achieve 2 kA of electron beam current, we have made several changes to the DARHT-II injector during 2006-2007. These changes resulted in a significant increase in the beam current, achieving the 2 kA milestone. Until recently (before 2007), the maximum beam current that was produced from the 6.5-inch diameter (612M) cathode was about 1300 A when the cathode was operating at a maximum temperature of 1140 C. At this temperature level, the heat loss was dominated by radiation which is proportional to temperature to the fourth power. The maximum operating temperature was limited by the damage threshold of the potted filament and the capacity of the filament heater power supply, as well as the shortening of the cathode life time. There were also signs of overheating at other components in the cathode assembly. Thus it was clear that our approach to increase beam current could not be simply trying to run at a higher temperature and the preferred way was to operate with a cathode that has a lower work function. The dispenser cathode initially used was the type 612M made by SpectraMat. According to the manufacturer's bulletin, this cathode should be able to produce more …
Date: March 9, 2009
Creator: Henestroza, E.; Houck, T.; Kwan, J. W.; Leitner, M.; Miram, G.; Prichard, B. et al.
Object Type: Report
System: The UNT Digital Library
DEMONSTRATION OF THE NEXT-GENERATION TCAP HYDROGEN ISOTOPE SEPARATION PROCESS (open access)

DEMONSTRATION OF THE NEXT-GENERATION TCAP HYDROGEN ISOTOPE SEPARATION PROCESS

The first generation of TCAP hydrogen isotope separation process has been in service for tritium separation at the Savannah River Site since 1994. To prepare for replacement, a next-generation TCAP process has been developed. This new process simplifies the column design and reduces the equipment requirements of the thermal cycling system. An experimental twelve-meter column was fabricated and installed in the laboratory to demonstrate its performance. This new design and its initial test results were presented at the 8th International Conference on Tritium Science and Technology and published in the proceedings. We have since completed the startup and demonstration the separation of protium and deuterium in the experimental unit. The unit has been operated for more than 200 cycles. A feed of 25% deuterium in protium was separated into two streams each better than 99.7% purity.
Date: January 9, 2009
Creator: Heung, L; Henry Sessions, H; Steve Xiao, S & Heather Mentzer, H
Object Type: Article
System: The UNT Digital Library
Design Considerations for a PEBB-Based Marx-Topology ILC Klystron Modulator (open access)

Design Considerations for a PEBB-Based Marx-Topology ILC Klystron Modulator

The concept of Power Electronic Building Blocks (PEBBs) has its origin in the U.S. Navy during the last decade of the past century. As compared to a more conventional or classical design approach, a PEBB-oriented design approach combines various potential advantages such as increased modularity, high availability and simplified serviceability. This relatively new design paradigm for power conversion has progressively matured since then and its underlying philosophy has been clearly and successfully demonstrated in a number of real-world applications. Therefore, this approach has been adopted here to design a Marx-topology modulator for an International Linear Collider (ILC) environment where easy serviceability and high availability are crucial. This paper describes various aspects relating to the design of a 32-cell Marx-topology ILC klystron modulator. The concept of nested droop correction is introduced and illustrated. Several design considerations including cosmic ray withstand, power cycling capability, fault tolerance, etc., are discussed. Details of the design of a Marx cell PEBB are included.
Date: December 9, 2009
Creator: Macken, K.; Beukers, T.; Burkhart, C.; Kemp, M. A.; Nguyen, M. N. & Tang, T.
Object Type: Article
System: The UNT Digital Library
Development and Characterization of a Thermodenuder for Aerosol Volatility Measurements (open access)

Development and Characterization of a Thermodenuder for Aerosol Volatility Measurements

This SBIR Phase I project addressed the critical need for improved characterization of carbonaceous aerosol species in the atmosphere. The proposed work focused on the development of a thermodenuder (TD) system capable of systematically measuring volatility profiles of primary and secondary organic aerosol species and providing insight into the effects of absorbing and nonabsorbing organic coatings on particle absorption properties. This work provided the fundamental framework for the generation of essential information needed for improved predictions of ambient aerosol loadings and radiative properties by atmospheric chemistry models. As part of this work, Aerodyne Research, Inc. (ARI) continued to develop and test, with the final objective of commercialization, an improved thermodenuder system that can be used in series with any aerosol instrument or suite of instruments (e.g., aerosol mass spectrometers-AMS, scanning mobility particle sizers-SMPS, photoacoustic absorption spectrometers-PAS, etc.) to obtain aerosol chemical, physical, and optical properties as a function of particle volatility. In particular, we provided the proof of concept for the direct coupling of our improved TD design with a full microphysical model to obtain volatility profiles for different organic aerosol components and to allow for meaningful comparisons between different TD-derived aerosol measurements. In a TD, particles are passed through …
Date: September 9, 2009
Creator: Onasch, Timothy
Object Type: Report
System: The UNT Digital Library
Discovery, Mineral Paragenesis and Origin of Wadalite in Meteorites (open access)

Discovery, Mineral Paragenesis and Origin of Wadalite in Meteorites

The mineral wadalite (ideal and simplified formula: Ca{sub 6}Al{sub 5}Si{sub 2}O{sub 16}Cl{sub 3}) has been discovered for the first time in a meteorite, specifically in the coarse-grained, igneous Type B calcium-aluminum-rich inclusions (CAIs) from the CV carbonaceous chondrite Allende. We report the results of electron microprobe, scanning electron microscopy and transmission electron microscopy analyses of wadalite-bearing assemblages in the Allende CAIs and propose that wadalite formed by metamorphic reaction between akermanitic melilite and anorthite, likely mediated by chlorine-bearing fluids. Petrographic relationships support the likelihood of multistage alterations by fluids of different chemistries interspersed or coinciding with thermal metamorphic episodes on the Allende parent asteroid. Fluid involvement in metamorphism of Allende CAIs implies that these objects experienced open-system alteration after accretion into the CV chondrite parent asteroid which may have resulted in disturbances of their oxygen- and magnesium-isotope systematics.
Date: July 9, 2009
Creator: Ishii, H A; Krot, A N; Bradley, J P; Keil, K; Nagashima, K; Teslich, N et al.
Object Type: Article
System: The UNT Digital Library