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Noise reduction of fuel pin images with a diffraction filter

Description: The quality of noisy images can be improved by summing several simular but statistically independent images that have been obtained either using a series of fluors in a stack intercepting the radiation from a single pinhole or by using multiple pinhole arrays or other coded apertures. An optical method of performing this addition is being explored for fuel pin imaging, and is presented here along with experimental results. In addition, the extension of this method to the simultaneous display of depth planes of a three-dimensional source is discussed.
Date: January 1, 1979
Creator: Miller, E.L. & Han, K.S.
Partner: UNT Libraries Government Documents Department

Dislocation accumulation at large plastic strains -- An approach to the theoretical strength of materials

Description: The usual method of introducing engineers to the concept of dislocations and their role in plastic flow is to compare an estimate of the theoretical strength of solid (of order {micro}/30 where {micro} is the shear modulus) and the observed strength of either single crystals ({mu}/10{sup 4}) or practical engineering material such as structural steels where the yield stress in shear is of order {mu}/10{sup 3}. However, if one considers the problem in reverse, one can consider the accumulation of dislocations as an important mechanism by which one can produce engineering materials in which the strength level approaches the theoretical strength. If one assumes that the flow stress can be expressed in terms of te mean free path between stored dislocations or as the square root of the global dislocation density, then one can see the influence of dislocation density in a diagrammatic form. It is clear that the strengthening by dislocation accumulation due to large imposed plastic strains represents an important approach both to the development of new, potentially valuable, engineering materials and an important area of basic understanding in terms of the mechanical response of materials close to their theoretical strength. Thus, this article will survey some of the factors which influence dislocation accumulation at large strains and the consequences of such accumulation processes.
Date: April 1, 1999
Creator: Embury, J.D. & Han, K.
Partner: UNT Libraries Government Documents Department

Waste inspection tomography (WIT)

Description: The WIT program will provide an inspection system that offers the nuclear waste evaluator a unique combination of tools for regulatory-driven characterization of low-level waste (LLW), transuranic waste (TRU), and mixed waste drums. WIT provides nondestructive, noninvasive, and environmentally safe inspections using X-ray and gamma ray technologies, with reasonable cost and throughput. Two emission imaging techniques will be employed for characterizing materials in waste containers. The first of these is gamma emission tomography, commonly called single-photon emission computed tomography (SPECT). Rather than using an external radiation source, SPECT uses the emission of radioactive materials within the object of interest for imaging. In this case, emission from actual nuclear waste within a container will provide a three-dimensional image of the radioactive substances in the container. The second emission technique will use high-purity germanium detectors for gamma ray spectroscopy. This technique, called nondestructive assay (NDA), can identify the emitting isotopic species and strength. Work in emission tomography and assay of nuclear waste has been undertaken at Lawrence Livermore National Laboratory using a technique called Passive Tomography. Results from a process development unit are presented.
Date: December 31, 1994
Creator: Bernardi, R.T. & Han, K.S.
Partner: UNT Libraries Government Documents Department

Technical description of the heterogeneous gas core reactor

Description: Solid-fueled and liquid-fueled heterogeneous nuclear reactors have already undergone extensive analysis and development. Gas-fueled nuclear reactor studies, however, have been restricted to either (1) homogeneous core systems, (2) two large separate regions of fuel and moderator; and (3) concentric rings of fuel-moderator arrangements. The gas-fueled heterogeneous core reactors consist of an array of coolant/moderator channels in a vessel containing a fissionable gas or a mixture of fissionable and non-fissionable gases. The moderator/coolant is, therefore, distributed in the core but physically separated from the gas. It is this moderator/coolant distribution in a variable lattice arrangement surrounded by the gas which constitutes the bases of this concept. The results of this arrangement on the neutron and fuel economy, power distribution, power density, and heat transfer characteristics have been found to be extremely advantageous. 13 figs.
Date: January 1, 1986
Creator: Diaz, N.J.; Dugan, E.T. & Han, K.I.
Partner: UNT Libraries Government Documents Department

Superconducting high-intensity RF proton accelerator for transmutation technologies

Description: Superconducting high-intensity RF proton accelerators with CW power of l00 MW can be used for transmutation technologies. Compared to a normal-conducting, room-temperature RF linac, a superconducting linac could produce substantial savings in operational cost. In this paper, we describe the design of such a linac.
Date: December 31, 1995
Creator: Han, K.C.; Garnett, R. & Gentzlinger, R.
Partner: UNT Libraries Government Documents Department

Development of materials related to the 60T and 100T magnets

Description: In the past year, the effort in materials science related to the 60T and 100T magnets at Los Alamos has been concentrated in three areas: (a) development of a fabrication route for Cu-Ag wire in collaboration with Handy and Harman and IGC and (b) investigation of the mechanical properties of a variety of potential high strength high conductivity materials (c) selection of the reinforcement materials for the coils and development of a fabrication route for these materials. The selection of the conductors and reinforcement materials is based on their mechanical properties and electrical properties at cryogenic temperature ({minus} 196 C). The authors have taken the approach of trying to relate the properties both to design requirements and to the service life of magnet. Thus, they have given some consideration both to the role of the internal stresses developed during the fabrication on the elastic-plastic transition and on the mechanical and thermal stability of heavily drawn wires. The feasibility of the fabrication route and the cost of manufacturing the materials must also be considered. They have emphasized the need to develop a fabrication route capable of producing the conductors with homogeneous mechanical and electrical properties and with a cross-section of 8.6 mm x 5.2 mm and 146 m in length or longer for a 100T magnet.
Date: December 31, 1997
Creator: Han, K. & Embury, J.D.
Partner: UNT Libraries Government Documents Department

Survey of Processing Methods for High Strength High Conductivity Wires for High Field Magnet Applications

Description: This paper will deal with the basic concepts of attaining combination of high strength and high conductivity in pure materials, in-situ composites and macrocomposites. It will survey current attainments, and outline where some future developments may lie in developing wire products that are close to the theoretical strength of future magnet applications.
Date: October 1, 1998
Creator: Han, K. & Embury, J.D.
Partner: UNT Libraries Government Documents Department

Comprehensive research on stability of amorphous silicon and alloy materials and devices. Annual report, May 31, 1995--May 30, 1996

Description: This report represents the progress achieved during the second year of our program to develop a-Si:H and a-(Si,Ge):H materials and devices with better stability by changing the chemistry of the growth technique. During this year, we have shifted our emphasis from cells made on tin oxide substrates (superstrate cells) to cells made on stainless steel substrates (substrate cells). The basic growth technique is to use a remote plasma beam of H or He, created by a low pressure ECR discharge, to create both growth and ion bombardment and/or etching during the growth of the films and devices. By inducing ion bombardment and etching, we can induce a more perfect lattice structure, and thereby improve the properties of the films and devices.
Date: August 1, 1997
Creator: Dalal, V.L.; Kaushal, S. & Han, K.
Partner: UNT Libraries Government Documents Department

Internal Stresses in Wires for High Field Magnets

Description: The codeformation of Cu-Ag or Cu-Nb composite wires used for high field magnets has a number of important microstructural consequences, including the production of very fine scale structures, the development of very high internal surface area to volume ratios during the drawing and the storage of defects at interphase interfaces. In addition, the fabrication and codeformation of phases which differ in crystal structure, thermal expansion, elastic modulus and lattice parameter lead to the development of short wavelength internal stresses. These internal stresses are measured by neutron diffraction and transmission electron microscopy as a function of the imposed drawing strain. The internal stresses lead to important changes in elastic plastic response which can be related to both magnet design and service life and these aspects will be described in detail.
Date: October 1, 1998
Creator: Han, K.; Embury, J.D.; Lawson, A.C.; Von Dreele, R.B.; Wood, J.T. & Richardson, J.W. Jr.
Partner: UNT Libraries Government Documents Department

Comprehensive Research on Stability of Amorphous Silicon and Alloy Materials and Devices

Description: In this report, the authors describe the work done to improve the material and device properties of a-Si:H and a-(Si,Ge):H alloys prepared using electron cyclotron resonance (ECR) plasma deposition and to understand the growth chemistry. Major results were obtained in the following areas: (1) Influence of plasma chemistry on properties and stability of a-Si:H single-junction solar cells; (2) Fabrication of good-quality tandem-junction cells. The authors made tandem-junction a-Si/a-Si cells with excellent voltages and fill factors using the H-ECR process; (3) Growth of high-quality a-(Si,Ge):H films using the ECR deposition process; (4) Fabrication of single-junction devices in a-(Si,Ge):H for diagnosing the material; and (5) Graded-gap cells in a-(Si,Ge):H. Good devices were produced using a graded-gap I-layer. In summary, the most important finding from this research has been that plasma chemistry plays a very important role in determining the properties of the materials, particularly the properties of the a-(Si,Ge):H alloy system. Even in a-Si:H, plasma chemistry plays a role in determining stability. This result suggests that by deliberately changing the chemistry of deposition, one may be able to further improve the a-(Si,Ge):H materials system and make its properties comparable to the properties of a-Si:H. The ECR reactor has proved to be a very useful chemical tool, with excellent control over growth chemistry.
Date: September 29, 2000
Creator: Dalal, V. K.; Han, K.; Maxson, T.; Girvan, R.; Kaushal, S.; DeBoer, S. et al.
Partner: UNT Libraries Government Documents Department

Fabrication Routes for High Strength High Conductivity Wires

Description: The development of suitable wires for magnet windings requires both the attainment of suitable combinations of properties (electrical conductivity and strength), the development of a production route capable of fabricating suitable quantity of wire of required dimension (5.2x7.6mm{sup 2} cross-section and 120 m in length) and a product with acceptable fabricability, joinability and service life. In this survey, the authors consider methods of producing suitable wire products by the codeformation of in-situ composites. This will include details of the quality control of the processing of Cu-Ag and Cu-Nb and the assessment of their detailed mechanical properties.
Date: October 1, 1998
Creator: Han, K.; Embury, J.D.; Sims, J.R.; Pantsyrnyi, V.I.; Shikov, A. & Bochvar, A.A.
Partner: UNT Libraries Government Documents Department

Megagauss Fields During Milliseconds

Description: A non-destructive, one megagauss magnet is now being designed in cooperation between Los Alamos and the National High Magnetic Field Laboratory (NHMFL) through joint funding by the US Department of Energy and the US NSF. The design combines two types of pulsed magnet now in use at the NHMFL: a capacitor-driven 'insert' magnet with a total pulse width of order 10 ms and a much larger 'outsert' magnet with a total pulse width of order 2 seconds that is driven by a controlled power source. The insert and outsert produce approximately 1/2 megagauss each. Although the design uses CuAg as the principal conductor further design efforts and materials development are exploring CuNb and stainless steel-clad copper as possible future alternatives. A crucial innovation was to employ wound steel strip (sheet) as a reinforcement in both insert and outsert coils. This gives extra strength due to the higher degree of cold-work possible in strip materials. For this leading edge magnet a key role is played by materials development. A major component, the 7 module 560 MVA controlled dc power supply required for the outsert, has been installed and commissioned.
Date: October 18, 1998
Creator: Campbell, L.J.; Embury, D.; Han, K.; Parkin, D.M.; Baca, A.; Kihara, K.H. et al.
Partner: UNT Libraries Government Documents Department

Measurement of the Double-Beta Decay Half-life of {sup 136}Xe in KamLAND-Zen

Description: We present results from the KamLAND-Zen double-beta decay experiment based on an exposure of 77.6 days with 129 kg of {sup 136}Xe. The measured two-neutrino double-beta decay half-life of {sup 136}Xe is T{sup 2{nu}}{sub 1/2} = 2:38 {+-}#6; 0:02(stat)#6;{+-}0.14(syst)#2;x10{sup 21} yr, consistent with a recent measurement by EXO-200. We also obtain a lower limit for the neutrinoless double-beta decay half-life, T{sup 0{nu}}{sub 1/2} > 5.7 x#2; 10{sup 24} yr at 90% C.L.
Date: January 23, 2012
Creator: Collaboration, KamLAND-Zen; Gando, A.; Gando, Y.; Hanakago, H.; Ikeda, H.; Inoue, K. et al.
Partner: UNT Libraries Government Documents Department

A study of extraterrestrial antineutrino sources with the KamLAND detector

Description: We present the results of a search for extraterrestrial electron antineutrinos ({bar {nu}}{sub e}'s) in the energy range 8.3 MeV < E{sub {bar {nu}}}{sub e} < 30.8 MeV using the KamLAND detector. In an exposure of 4.53 kton-year, we identify 25 candidate events. All of the candidate events can be attributed to background, most importantly neutral current atmospheric neutrino interactions, setting an upper limit on the probability of {sup 8}B solar {nu}{sub e}'s converting into {bar {nu}}{sub e}'s at 5.3 x 10{sup -5} (90% C.L.). The present data also allows us to set more stringent limits on the diffuse supernova neutrino flux and on the annihilation rates for light dark matter particles.
Date: May 18, 2011
Creator: Collaboration, The KamLAND; Gando, A.; Gando, Y.; Ichimura, K.; Ikeda, H.; Inoue, K. et al.
Partner: UNT Libraries Government Documents Department

Enhanced Constraints on theta13 from A Three-Flavor Oscillation Analysis of Reactor Antineutrinos at KamLAND

Description: We present new constraints on the neutrino oscillation parameters {Delta}m{sub 21}{sup 2}, {theta}{sub 12}, and {theta}{sub 13} from a three-flavor analysis of solar and KamLAND data. The KamLAND data set includes data acquired following a radiopurity upgrade and amounts to a total exposure of 3.49 x 10{sup 32} target-proton-year. Under the assumption of CPT invariance, a two-flavor analysis ({theta}{sub 13} = 0) of the KamLAND and solar data yields the best-fit values tan{sup 2} {theta}{sub 12} = 0.444{sub -0.030}{sup +0.036} and {Delta}m{sub 21}{sup 2} = 7.50{sub -0.20}{sup +0.19} x 10{sup -5} eV{sup 2}; a three-flavor analysis with {theta}{sub 13} as a free parameter yields the best-fit values tan{sup 2} {theta}{sub 12} = 0.452{sub -0.033}{sup +0.035}, {Delta}m{sub 21}{sup 2} = 7.50{sub -0.20}{sup +0.19} x 10{sup -5}eV{sup 2}, and sin{sup 2} {theta}{sub 13} = 0.020{sub -0.016}{sup +0.016}. This {theta}{sub 13} interval is consistent with other recent work combining the CHOOZ, atmospheric and long-baseline accelerator experiments. We also present a new global {theta}{sub 13} analysis, incorporating the CHOOZ, atmospheric and accelerator data, which indicates sin{sup 2} {theta}{sub 13} = 0.017{sub -0.009}{sup +0.010}, a nonzero value at the 93% C.L. This finding will be further tested by upcoming accelerator and reactor experiments.
Date: September 24, 2010
Creator: Collaboration, The KamLAND; Gando, A.; Gando, Y.; Ichimura, K.; Ikeda, H.; Inoue, K. et al.
Partner: UNT Libraries Government Documents Department

Measurement of the 8B Solar Neutrino Flux with KamLAND

Description: We report a measurement of the neutrino-electron elastic scattering rate from {sup 8}B solar neutrinos based on a 123 kton-day exposure of KamLAND. The background-subtracted electron recoil rate, above a 5.5-MeV analysis threshold is 1.49 {+-} 0.14(stat) {+-} 0.17(syst) events per kton-day. Interpreted as due to a pure electron flavor flux with a {sup 8}B neutrino spectrum, this corresponds to a spectrum integrated flux of 2.77 {+-} 0.26(stat) {+-} 0.32(syst) x 10{sup 6} cm{sup -2}s{sup -1}. The analysis threshold is driven by {sup 208}Tl present in the liquid scintillator, and the main source of systematic uncertainty is due to background from cosmogenic {sup 11}Be. The measured rate is consistent with existing measurements and with standard solar model predictions which include matter-enhanced neutrino oscillation.
Date: June 4, 2011
Creator: Abe, S.; Furuno, K.; Gando, A.; Gando, Y.; Ichimura, K.; Ikeda, H. et al.
Partner: UNT Libraries Government Documents Department

Sensitivity of CUORE to Neutrinoless Double-Beta Decay

Description: In this paper, we study the sensitivity of CUORE, a bolometric double-beta decay experiment under construction at the Laboratori Nazionali del Gran Sasso in Italy. Two approaches to the computation of experimental sensitivity are discussed and compared, and the formulas and parameters used in the sensitivity estimates are provided. Assuming a background rate of 10{sup -2} cts/(keV kg y), we find that, after 5 years of live time, CUORE will have a 1#27;{sigma} sensitivity to the neutrinoless double-beta decay half-life of {caret T{sup 0{nu}}{sub 1/2}}(1{sigma}#27;) = 1.6x#2;10{sup 26} y and thus a potential to probe the effective Majorana neutrino mass down to 41-95 meV; the sensitivity at 1.64{sigma}#27;, which corresponds to 90% C.L., will be {caret T{sup 0{nu}}{sub 1/2}(1.64{sigma}#27;}) = 9.5x10{sup 25} y. This range is compared with the claim of observation of neutrinoless double-beta decay in {sup 76}Ge and the preferred range in the neutrino mass parameter space from oscillation results.
Date: November 23, 2011
Creator: CUORE; Alessandria, F.; Andreotti, E.; Ardito, R.; Arnaboldi, C.; Avignone III, F. T. et al.
Partner: UNT Libraries Government Documents Department