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An overview of spin physics (open access)

An overview of spin physics

Spin physics is playing an increasingly important role in high energy experiments and theory. This review looks at selected topics in high energy spin physics that were discussed at the 9th International Symposium on High Energy Spin Physics at Bonn in September 1990.
Date: July 1, 1991
Creator: Prescott, C. Y.
System: The UNT Digital Library
Fractional activation of accumulation-mode particles in warm continental stratiform clouds (open access)

Fractional activation of accumulation-mode particles in warm continental stratiform clouds

The degree of activation of accumulation-mode particles (AMP) in clouds has been studied using continuous (1 second average) aircraft measurements of the number concentrations of cloud droplets (N{sub cd}, 2 to 35 {mu}m diameter) and of unactivated AMP (N{sub amp}, 0.17 to 2.07 {mu}m diameter) in cloud interstitial air. The magnitude and spatial variation of the activated fraction (F) of all measured particles (defined as F {triple_bond} N{sub cd}/N{sub tot}, where N{sub tot} = N{sub cd} + N{sub amp}) are investigated, based on measurements made during ten aircraft flights in non-precipitating warm continental stratiform clouds near Syracuse NY in the fall of 1984. Based on instantaneous observations throughout the clouds, the spatial distribution of F was found to be quite nonuniform. In general, F was low in cloud edges and where total particle loading was high and/or cloud convective activity was low. In the interior of clouds, the value of F exceeded 0.9 for 36% of the data, but was below 0.6 for 28%. Factors influencing F the most were the total particle loading (N{sub tot}) and the thermal stability of the cloud layer. The dependence of F on N{sub tot} in cloud interior was characterized by two distinct regimes. …
Date: July 1, 1991
Creator: Gillani, N. V.; Daum, P. H.; Schwartz, S. E.; Leaitch, W. R.; Strapp, J. W. & Isaac, G. A.
System: The UNT Digital Library
Modelling and evaluating against the violent insider (open access)

Modelling and evaluating against the violent insider

The violent insider threat poses a special challenge to facilities protecting special nuclear material from theft or diversion. These insiders could potentially behave as nonviolent insiders to deceitfully defeat certain safeguards elements and use violence to forcefully defeat hardware or personnel. While several vulnerability assessment tools are available to deal with the nonviolent insider, very limited effort has been directed to developing analysis tools for the violent threat. In this paper, we present an approach using the results of a vulnerability assessment for nonviolent insiders to evaluate certain violent insider scenarios. Since existing tools do not explicitly consider violent insiders, the approach is intended for experienced safeguards analysts and relies on the analyst to brainstorm possible violent actions, to assign detection probabilities, and to ensure consistency. We then discuss our efforts in developing an automated tool for assessing the vulnerability against those violent insiders who are willing to use force against barriers, but who are unwilling to kill or be killed. Specifically, we discuss our efforts in developing databases for violent insiders penetrating barriers, algorithms for considering the entry of contraband, and modelling issues in considering the use of violence.
Date: July 1, 1991
Creator: Fortney, D. S.; Al-Ayat, R. A. & Saleh, R. A.
System: The UNT Digital Library
Using a straightness reference in obtaining more accurate surface profiles from a Long Trace Profiler (open access)

Using a straightness reference in obtaining more accurate surface profiles from a Long Trace Profiler

The Long Trace Profiler has found significant applications in measuring the surfaces of synchrotron optics. However, requirements of small slope errors at all spatial wavelengths of the synchrotron optics mandate more accurate slope measurements. A straightness reference for the Long Trace Profiler greatly increases the accuracy of the instrument. Methods of using the straightness reference by interpreting the sequential interference patterns are discussed and results of measurements are presented.
Date: July 15, 1991
Creator: Irick, S. C.; McKinney, W. R.; Lunt, D. L. J. & Takacs, P. Z.
System: The UNT Digital Library
An overview of spin physics (open access)

An overview of spin physics

Spin physics is playing an increasingly important role in high energy experiments and theory. This review looks at selected topics in high energy spin physics that were discussed at the 9th International Symposium on High Energy Spin Physics at Bonn in September 1990.
Date: July 1, 1991
Creator: Prescott, C. Y.
System: The UNT Digital Library
Determining surface profile from sequential interference patterns from a long trace profiler (open access)

Determining surface profile from sequential interference patterns from a long trace profiler

The Long Trace Profiler (Takacs et al.) is a slope-measuring instrument which was introduced several years ago. Development of this instrument continues at Lawrence Berkeley Laboratory in improving both hardware design and software algorithms for turning the raw interference data (a sequence of intensity patterns) into properly interpreted representations of surface slope and height. This report presents a mathematical model of the interference pattern and methods of extracting the slope and height profile from such patterns. 9 refs.
Date: July 1, 1991
Creator: Irick, S. C.
System: The UNT Digital Library
Evaluating the anomaly resolution capability of an MC&A system (open access)

Evaluating the anomaly resolution capability of an MC&A system

Discrepancies in accounting for Special Nuclear Material (SNM) require quick and accurate resolution. The ability to make a definitive resolution often depends on the types of measurement data available and on the way records are maintained in the Material Control and Accounting (MC&A) system. A new method is presented for systematically evaluating the overall anomaly detection and resolution capability of an MC&A system. The method begins with a detailed specification of the material process cycle including, all authorized material locations, possible unauthorized locations, and the procedures for measuring and recording movement between locations. The analysis proceeds by identifying the types of errors that could logically occur in the measurement and recording system and estimating their frequency. A method is described for quantifying the detection capability and resolution effectiveness for each possible error. A new metric is also proposed for quantifying the overall effectiveness of the MC&A system.
Date: July 1, 1991
Creator: Saleh, R. & Smith, G.
System: The UNT Digital Library
Gamma-ray spectrometry of LDEF samples at SRL (open access)

Gamma-ray spectrometry of LDEF samples at SRL

A total of 31 samples from the Long Duration Exposure Facility (LDEF), including materials of aluminum, vanadium, and steel trunnions were analyzed by ultra-low-level gamma spectroscopy. The study quantified particle induced activations of {sup 22}Na, {sup 46}Sc, {sup 51}Cr, {sup 54}Mn, {sup 56}Co, {sup 57}Co, {sup 58}Co, and {sup 60}Co. The samples of trunnion sections exhibited increasing activity toward the outer end of the trunnion and decreasing activity toward its radial center. The trunnion sections did not include end pieces, which have been reported to collect noticeable {sup 7}Be on their leading surfaces. No significant {sup 7}Be was detected in the samples analyzed. The Underground Counting Facility at Savannah River Laboratory (SRL) was used in this work. The facility is 50 ft. underground, constructed with low-background shielding materials, and operated as a clean room. The most sensitive analyses were performed with a 90%-efficient HPGe gamma-ray detector, which is enclosed in a purged active/passive shield. Each sample was counted for one to six days in two orientations to yield more representative average activities for the sample. The non-standard geometries of the LDEF samples prompted the development of a novel calibration method, whereby the efficiency about the samples surfaces (measured with point …
Date: July 22, 1991
Creator: Winn, W. G.
System: The UNT Digital Library
High-LET charged particle radiotherapy (open access)

High-LET charged particle radiotherapy

The Department of Radiation Oncology at UCSF Medical Center and the Radiation Oncology Department at UC Lawrence Berkeley Laboratory have been evaluating the use of high LET charged particle radiotherapy in a Phase 1--2 research trial ongoing since 1979. In this clinical trail, 239 patients have received at least 10 Gy (physical) minimum tumor dose with neon ions, meaning that at least one-half of their total treatment was given with high-LET charged particle therapy. Ninety-one patients received all of their therapy with neon ions. Of the 239 patients irradiated, target sites included lesions in the skin, subcutaneous tissues, head and neck such as paranasal sinuses, nasopharynx and salivary glands (major and minor), skull base and juxtaspinal area, GI tract including esophagus, pancreas and biliary tract, prostate, lung, soft tissue and bone. Analysis of these patients has been carried out with a minimum followup period of 2 years.
Date: July 1, 1991
Creator: Castro, J. R.
System: The UNT Digital Library
Effluent Treatment Facility tritium emissions monitoring (open access)

Effluent Treatment Facility tritium emissions monitoring

An Environmental Protection Agency (EPA) approved sampling and analysis protocol was developed and executed to verify atmospheric emissions compliance for the new Savannah River Site (SRS) F/H area Effluent Treatment Facility. Sampling equipment was fabricated, installed, and tested at stack monitoring points for filtrable particulate radionuclides, radioactive iodine, and tritium. The only detectable anthropogenic radionuclides released from Effluent Treatment Facility stacks during monitoring were iodine-129 and tritium oxide. This paper only examines the collection and analysis of tritium oxide.
Date: July 25, 1991
Creator: Dunn, D. L.
System: The UNT Digital Library
Thermodynamics of aqueous sodium sulfate from the temperatures 273 K to 373 K and mixtures of aqueous sodium sulfate and sulfuric acid at 298.15 K (open access)

Thermodynamics of aqueous sodium sulfate from the temperatures 273 K to 373 K and mixtures of aqueous sodium sulfate and sulfuric acid at 298.15 K

New isopiestic vapor-pressure measurements on the aqueous system {l_brace}(1{minus}y)H{sub 2}SO{sub 4}+yNA{sub 2}SO{sub 4}{r_brace} along with earlier experimental investigations that span the range from y=0 to y=1 and infinitely dilute to supersaturated molalities have been analyzed in terms of the Pitzer ion-interaction model. Refined ion-interaction parameters for aqueous sodium sulfate valid over the temperature range 273 K to 373 K have been calculated and used for analyzing results for mixtures containing sulfuric acid and sodium sulfate at 298.15 K. Analysis of experimental results for these aqueous mixtures required explicit consideration of the dissociation reaction of bisulfate ion. Previous treatments of aqueous sulfuric acid and subsequently the bisulfate dissociation equilibrium valid in the range 273 K to 343 K were employed as a first approximation in representing the mixed solutions. Two sets of Pitzer ion-interaction parameters are presented for (sodium sulfate + sulfuric acid). The validity of the first set is limited in ionic strength and molality to saturated solutions of pure aqueous sodium sulfate (4 mol{center_dot}kg{sup {minus}1}). The second set of parameters corresponds to a slightly less precise representation but is valid over the entire range of experimental results considered. Both sets of parameters provide a more complete description of pure …
Date: July 1991
Creator: Hovey, J. K.; Pitzer, K. S. & Rard, J. A.
System: The UNT Digital Library
Design integration of favorable geometry, structural support and containment (open access)

Design integration of favorable geometry, structural support and containment

In designs for fissile processes at Savannah River site, different approaches have been used to provide engineered margins of safety for criticality with containment and seismic resistance as additional requirements. These requirements are frequently at odds in engineered systems. This paper proposes a plan to take advantage of vessels with favorable geometry to provide seismic resistance and to support a glovebox for containment. Thin slab tanks, small diameter pencil tanks, annular tanks, and other novel designs have been used for criticality safety. The requirement for DBE seismic resistance and rigid control of dimensions leads the designer to consider annular tanks for meeting these requirements. The high strength of annular tanks may logically be used to support secondary containment. Hands-on access to all instruments, piping etc. within containment can be provided through gloveports, thus a specialized glovebox. This paper examines the advantages of using an annular tank design to provide favorable geometry, structural support and containment.
Date: July 1, 1991
Creator: Purcell, J. A. & McGehee, G. A.
System: The UNT Digital Library
X-ray diffraction study of GaSb/AlSb strained-layer-superlattices grown on miscut (100) substrates (open access)

X-ray diffraction study of GaSb/AlSb strained-layer-superlattices grown on miscut (100) substrates

A series of superlattices were grown by molecular beam epitaxy on (100) GaSb substrates which had been miscut by 2, 3, and 4 degrees toward the <011> direction. These superlattices were then studied by scanning all possible [444] or [511] (asymmetric) reflections with high resolution multiple-crystal x-ray diffractometry. In addition, the (400) (quasi-symmetric) reflection was scanned. From peak splittings we extracted mismatch and tilt parameters for the epitaxial unit cell. We compared our results for the non-tetragonal component of the distortion ot calculations based on the coherent strain model of Hornstra and Bartels (J. Cryst. Growth 44,513 (1978)). We find that this model which was developed for epitaxial growth on a general (hkl) plane also describes our results for growth on vicinal (100) planes. The resolution of our data is sufficient to establish that the distortion was not purely tetragonal. A monoclinic unit cell symmetry adequately describes our results.
Date: July 1, 1991
Creator: Macrander, A. T.; Schwartz, G. P.; Guiltieri, G. J. & Gilmer, G.
System: The UNT Digital Library
Precipitation scavenging models: Sensitivities, tests, and applications (open access)

Precipitation scavenging models: Sensitivities, tests, and applications

``Multiphase`` atmospheric-chemistry models can be described as atmospheric-pollutant simulations that explicitly differentiate between physical phases in the atmosphere (.e.g., gas, cloud water, rain water, snow,...), and directly compute chemical transport and transformation behavior between and within each of these individual phases. Initially formulated for specific application to precipitation-scavenging analysis, many attributes of these models have become incorporated into the more general atmospheric-chemisty codes as well. During the past few years, several of these multiphase precipitation-scavenging models have been developed to the point where they can be applied, in a moderately straightforward fashion, by members of the extended atmospheric sciences community. This presentation provides a brief overview of several aspects of a number of these models, including their structure, their application, their sensitivities and uncertainty levels, their evaluation against field measurements, and their availability.
Date: July 1, 1991
Creator: Hales, J. M.
System: The UNT Digital Library
HREM imaging of single unit cell carbide precipitates in Pt-C alloys (open access)

HREM imaging of single unit cell carbide precipitates in Pt-C alloys

Dilute Pt-C alloys are prototypical for studying oversize carbide phase precipitation from interstitial solid solution. Earlier studies showed the essential function of quenched-in vacancies in the precipitation process. Vacancies play a dual, volume accommodation and structural role in the transformation by modifying both the habit plane spacing and stacking sequence. It was also shown how the precipitation sequence in interstitial Pt-C alloys is analogous to that in substitutional Al-Cu alloys. Initially a ``GP zone`` consisting of a monolayer plate of carbon atoms and vacancies forms. Atomic resolution images of the so-called {alpha} precipitates have confirmed their structure. During subsequent coarsening of the precipitates, {alpha}{prime} platelets form. The single-layer {alpha} structure, or GP zone is identical to a {l_brace}100{r_brace} stacking fault stabilized by an intercalation of carbon. The two-layer {alpha}{prime} structure is the first true precipitate phase and has a crystal structure anti-isomorphous with calcium fluoride. In the present contribution, simulated images based on this structure are compared with experimental images obtained at 800kV on the JEOL-1000 ARM. In addition to confirming the proposed precipitate structure, the results show the potential for successful imaging of precipitate structures containing light elements. 4 refs., 3 figs.
Date: July 1, 1991
Creator: Witcomb, M. J.; Dahmen, U.; O`Keefe, M. A. & Westmacott, K. H.
System: The UNT Digital Library
Structure and dynamical nature of hot and dense QCD matter (open access)

Structure and dynamical nature of hot and dense QCD matter

Static and dynamical properties of QCD at finite temperature and density are reviewed. Non-perturbative aspects of the QCD plasma and the modification of the hadron properties associated with the chiral transition are discussed on the basis of lattice data, effective theories and QCD sum rules. Special emphasis is laid on the importance of the finite baryon density to see the effects of the restoration of chiral symmetry in experiment.
Date: July 1, 1991
Creator: Hatsuda, Tetsuo
System: The UNT Digital Library
A comparison of policies to mitigate US greenhouse gas emissions (open access)

A comparison of policies to mitigate US greenhouse gas emissions

The Congress of the United States requested that the Secretary of Energy: Prepare a report for the Congress that comprehensively inventories the sources of carbon dioxide (CO{sub 2}) and arranges the policy options to be formulated in cooperation with the Environmental Protection Agency (including, but not limited to, energy pricing, energy efficiency requirements, alternative fuels, alternative end use, and supply technology) which would lead to a substantial reduction in CO{sub 2} emissions. This paper summarizes work in progress to respond to the Congressional request. Further, it builds on the DOE`s first National Energy Strategy (NES) (DOE 191). As a result of the substantial research effort in support of this report, five major conclusions are drawn and discussed.
Date: July 1, 1991
Creator: Edmonds, J. A.; McDonald, S. C. & Bradley, R. A.
System: The UNT Digital Library
Applications of synchrotron radiation to Chemical Engineering Science: Workshop report (open access)

Applications of synchrotron radiation to Chemical Engineering Science: Workshop report

None
Date: July 1, 1991
Creator: unknown
System: The UNT Digital Library
Coil end design for the SSC collider dipole magnet (open access)

Coil end design for the SSC collider dipole magnet

This paper describes the design of the coil end for the 50mm aperture SSC collider dipole magnets built at Fermilab. The cable paths are determined from both magnetic and mechanical considerations. The end spacers are designed using the developable surface, grouped end approach, which allows the analysis of strain energy within the conductor groups. Techniques for strain energy minimization are presented and the behavior of individual conductors within a group is analyzed. The relationship between optimization of magnetic and mechanical variables is discussed. Requirements of manufacturing and inspection of coil end parts are outlined. 7 refs.
Date: July 1, 1991
Creator: Brandt, J.; Bartlett, N.; Bossert, R.; Carson, J.; Konc, J.; Lee, G. et al.
System: The UNT Digital Library
Varied line-space gratings and applications (open access)

Varied line-space gratings and applications

This paper presents a straightforward analytical and numerical method for the design of a specific type of varied line-space grating system. The mathematical development will assume plane or nearly-plane spherical gratings which are illuminated by convergent light, which covers many interesting cases for synchrotron radiation. The gratings discussed will have straight grooves whose spacing varies across the principal plane of the grating. Focal relationships and formulae for the optical grating-pole-to-exist-slit distance and grating radius previously presented by other authors will be derived with a symbolic algebra system. It is intended to provide the optical designer with the tools necessary to design such a system properly. Finally, some possible advantages and disadvantages for application to synchrotron to synchrotron radiation beamlines will be discussed.
Date: July 15, 1991
Creator: McKinney, W. R.
System: The UNT Digital Library
Meteorological and chemical factors controlling the composition of precipitation in eastern North America (open access)

Meteorological and chemical factors controlling the composition of precipitation in eastern North America

Precipitation in eastern North America is characterized by high concentrations of free acidity and sulfate that are generally attributed to anthropogenic air pollution. The relatively long record of precipitation chemistry measurements at the Penn State MAP3S site is used to analyze the seasonal and interannual variability of precipitation composition in terms of specific mechanisms of atmospheric transport and chemical transformation. The interrelationships of the chemical variables in the precipitation record and in recent air measurements clearly link the precipitation acidity with the wet deposition of sulfate derived from the in-cloud oxidation of sulfur dioxide. High-deposition events are shown through meteorological trajectory analyses to be associated with moist air from the Gulf of Mexico that passes through the upper midwestern parts of the United States. The main chemical factor controlling the deposition of sulfate appears to be the availability of strong oxidants for transforming dissolved sulfur dioxide into aqueous sulfate. Excess sulfur dioxide is expected to exit the storm systems at high altitudes and experience truly long-range transport. This interpretation of the data gives confidence that episodes will occur even after sulfur dioxide emissions have been reduced substantially.
Date: July 1, 1991
Creator: Lamb, D. & Comrie, L.
System: The UNT Digital Library
Hazardous chemical and radioactive wastes at Hanford (open access)

Hazardous chemical and radioactive wastes at Hanford

The Hanford Site was established in 1944 to produce plutonium for defense. During the past four decades, a number of reactors, processing facilities, and waste management facilities have been built at Hanford for plutonium production. Generally, Hanford`s 100 Area was dedicated to reactor operation; the 200 Area to fuel reprocessing, plutonium recovery, and waste management; and the 300 Area to fuel fabrication and research and development. Wastes generated from these operations included highly radioactive liquid wastes, which were discharged to single- and double-shell tanks; solid wastes, including both transuranic (TRU) and low-level wastes, which were buried or discharged to caissons; and waste water containing low- to intermediate-level radioactivity, which was discharged to the soil column via near-surface liquid disposal units such as cribs, ponds, and retention basins. Virtually all of the wastes contained hazardous chemical as well as radioactive constituents. This paper will focus on the hazardous chemical components of the radioactive mixed waste generated by plutonium production at Hanford. The processes, chemicals used, methods of disposition, fate in the environment, and actions being taken to clean up this legacy are described by location.
Date: July 1, 1991
Creator: Keller, J. F. & Stewart, T. L.
System: The UNT Digital Library
Fast neutron irradiation effects on magnetization relaxation in YBCO single crystals (open access)

Fast neutron irradiation effects on magnetization relaxation in YBCO single crystals

A high-quality YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} single crystal has been investigated by torque magnetometry prior to and following fast neutron irradiation to a fluence of 2{times}10{sup 21} m{sup {minus}2} (E > 0.1 MeV). In addition to large enhancements of the critical current densities, which have been observed in similar form previously by Sauerzopf et al, we find a dramatic change in the relaxation behavior following irradiation. At low temperatures ({le} 50 k) the relaxation rates are lowered by factors up to 4 in the irradiated state in a magnetic field of 1.5 T. At higher temperatures, on the other hand, they are enhanced compared to the unirradiated state. Both before and after irradiation, the magnetization relaxation follows a logarithmic time dependence, which we ascribe to thermally activated flux motion.
Date: July 1, 1991
Creator: Lensink, J. G.; Griessen, R.; Wiesinger, H. P.; Sauerzopf, F. M.; Weber, H. W. & Crabtree, G. W.
System: The UNT Digital Library
HREM imaging of single unit cell carbide precipitates in Pt-C alloys (open access)

HREM imaging of single unit cell carbide precipitates in Pt-C alloys

Dilute Pt-C alloys are prototypical for studying oversize carbide phase precipitation from interstitial solid solution. Earlier studies showed the essential function of quenched-in vacancies in the precipitation process. Vacancies play a dual, volume accommodation and structural role in the transformation by modifying both the habit plane spacing and stacking sequence. It was also shown how the precipitation sequence in interstitial Pt-C alloys is analogous to that in substitutional Al-Cu alloys. Initially a GP zone'' consisting of a monolayer plate of carbon atoms and vacancies forms. Atomic resolution images of the so-called {alpha} precipitates have confirmed their structure. During subsequent coarsening of the precipitates, {alpha}{prime} platelets form. The single-layer {alpha} structure, or GP zone is identical to a {l brace}100{r brace} stacking fault stabilized by an intercalation of carbon. The two-layer {alpha}{prime} structure is the first true precipitate phase and has a crystal structure anti-isomorphous with calcium fluoride. In the present contribution, simulated images based on this structure are compared with experimental images obtained at 800kV on the JEOL-1000 ARM. In addition to confirming the proposed precipitate structure, the results show the potential for successful imaging of precipitate structures containing light elements. 4 refs., 3 figs.
Date: July 1991
Creator: Witcomb, M. J.; Dahmen, U.; O'Keefe, M. A. & Westmacott, K. H.
System: The UNT Digital Library