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Recovery of deformed and hydrogen-charge palladium (open access)

Recovery of deformed and hydrogen-charge palladium

Positron lifetime and Doppler-broadening studies made at 300 K have been used to investigate the interaction between interstitial hydrogen and lattice defects in deformed Pd. Specimens were charged with hydrogen at 300 K to levels up to 0.1%. The presence of hydrogen was found to have no effect on the recovery curves of Pd upon annealing to 400/sup 0/C. By 400/sup 0/C the values for both lifetime and Doppler-broadening for both cold worked and cold worked plus hydrogen were below the values obtained for annealed pure Pd. This can be interpreted as gaseous-impurity-trapped vacancies being present after the 1200/sup 0/C anneal, but being swept away by the dislocation microstructure recovery between 200 to 400/sup 0/C.
Date: January 1, 1982
Creator: Snead, C. L. Jr.; Lynn, K. G. & Lynch, J. F.
Object Type: Article
System: The UNT Digital Library
Excitation of giant resonances via direct reactions (open access)

Excitation of giant resonances via direct reactions

Experimental measurements of electric giant multipole resonances are discussed. The parameters of the giant quadrupole resonance are now firmly established by an extensive set of measurements. The GQR is providing a significant influence in other areas of nuclear physics. The monopole resonance has now been established and its observation has provided the first direct measure of the nuclear compressibility. A strong case for the existence of a giant octupole resonance is now being made through a variety of hadron reactions. However, the supply of giant multipole resonances has not been exhausted. The newer techniques such as higher energy proton scattering, charge exchange reactions, heavy-ion scattering and pion reactions offer considerable hope for identifying new resonances during the next few years.
Date: January 1, 1982
Creator: Bertrand, F.E.
Object Type: Article
System: The UNT Digital Library
Picotron 100 streak tubes as a 150-channel photometer (open access)

Picotron 100 streak tubes as a 150-channel photometer

The characterization of a streak camera based upon Picotron 100 tube types is given. Both a large (30 cm 1 x 10 cm dia.) and a small (18 cm 1 x 5 cm dia.) version of this design has been tested. Over 150 channels of information are simultaneously time resolved with system S.N.R. of 3 at 100 picosecond time resolution without post intensification. Absolute photometric evaluation is given in the dynamic mode, i.e. while operating in the picosecond time domain. Such quantitative data has been lacking in the past, particularly for multiple channel applications.
Date: January 1, 1982
Creator: Majumdar, S.; Weiss, P.B. & Black, J.P.
Object Type: Article
System: The UNT Digital Library
Laser-plasma interaction experiments at laser wavelengths of 1. 064. mu. m, 0. 532. mu. m, and 0. 355. mu. m (open access)

Laser-plasma interaction experiments at laser wavelengths of 1. 064. mu. m, 0. 532. mu. m, and 0. 355. mu. m

The effect of laser wavelength on laser-plasma coupling is one of the critical issues facing the laser driven inertial confinement community. The advantages of using lasers with output wavelength less than 1 ..mu..m, such as enhanced absorption and hydrodynamic efficiency, reduction in parametric instabilities and corresponding suprathermal electron generation, have long been predicted theoretically.
Date: January 1, 1982
Creator: Campbell, E. M.; Mead, W. C. & Turner, R. E.
Object Type: Article
System: The UNT Digital Library
Growth regulation by macrophages (open access)

Growth regulation by macrophages

The evidence reviewed here indicates that macrophages, either acting alone or in concert with other cells, influence the proliferation of multiple types of cells. Most of the data indicate that these effects are mediated by soluble macrophage-elaborated products (probably proteins) although the role of direct cell-to-cell contacts cannot be ruled out in all cases. A degree of success has been achieved on the biochemical characterization of these factors, due mainly to their low specific activity in conditioned medium and the lack of rapid, specific assays. Understanding the growth-regulating potential of macrophages is an important and needed area of research.
Date: January 1, 1982
Creator: Wharton, W.; Walker, E. & Stewart, C.C.
Object Type: Article
System: The UNT Digital Library
Diskless LSI-11 systems (open access)

Diskless LSI-11 systems

Programs for dedicated LSI-11 based systems can easily be stored in ROM instead of floppy disks, yet execute the same as disk-stored programs. Two sample systems are described.
Date: January 1, 1982
Creator: Ford, W. & Shirk, D. G.
Object Type: Article
System: The UNT Digital Library
Statistical magnetohydrodynamics and reversed-field-pinch quiescence (open access)

Statistical magnetohydrodynamics and reversed-field-pinch quiescence

A statistical model of a bounded, incompressible, cylindrical magnetofluid is presented. This model predicts the presence of magnetic fluctuations about a cylindrically-symmetric, Bessel-function-model, mean magnetic field, which satisfies del x <B> = ..mu.. <B>. As theta ..-->.. 1.56, the model predicts that the significant region of the fluctuation spectrum narrows down to a single (coherent) m = 1 mode. An analogy between the Debye length of an electrostatic plasma and ..mu../sup -1/ suggests the physical validity o the model's prediction of <deltaB(r)deltaB(r')> when /r - r'/ greater than or equal to ..mu../sup -1/.
Date: January 1, 1982
Creator: Turner, L.
Object Type: Article
System: The UNT Digital Library
Development of 400- to 450-MHz RFQ resonator-cavity mechanical designs (open access)

Development of 400- to 450-MHz RFQ resonator-cavity mechanical designs

In the development of the radio-frequency quadrupole (RFQ) linac, the resonator cavity's mechanical design may be a challenge similar in magnitude to that of the development of the accelerator structure itself. Experience with the all-copper 425-MHz RFQ proof-of-principle linac has demonstrated that the resonator cavity must be structurally stiff and easily tunable. This experience has led to development of copper-plated steel structures having vanes that may be moved within a cylinder for tuning. Design of a flexible vane-to-cylinder radio-frequency (rf) joint, the vane, and the cylinder has many constraints dictated by the small-diameter cavities in the 400-MHz-frequency region. Two types of flexible, mechanical vane-to-cylinder rf joints are being developed at Los Alamos: the C-seal and the rf clamp-joint.
Date: January 1, 1982
Creator: Hansborough, L.D.
Object Type: Report
System: The UNT Digital Library
Use of principal components analysis and three-dimensional atmospheric-transport models for reactor-consequence evaluation (open access)

Use of principal components analysis and three-dimensional atmospheric-transport models for reactor-consequence evaluation

This work explores the use of principal components analysis coupled to three-dimensional atmospheric transport and dispersion models for evaluating the environmental consequences of reactor accidents. This permits the inclusion of meteorological data from multiple sites and the effects of topography in the consequence evaluation; features not normally included in such analyses. The technique identifies prevailing regional wind patterns and their frequencies for use in the transport and dispersion calculations. Analysis of a hypothetical accident scenario involving a release of radioactivity from a reactor situated in a river valley indicated the technique is quite useful whenever recurring wind patterns exist, as is often the case in complex terrain situations. Considerable differences were revealed in a comparison with results obtained from a more conventional Gaussian plume model using only the reactor site meteorology and no topographic effects.
Date: January 1, 1982
Creator: Gudiksen, P. H.; Walton, J. J.; Alpert, D. J. & Johnson, J. D.
Object Type: Article
System: The UNT Digital Library
Selective population of high-j states via heavy-ion-induced transfer reactions (open access)

Selective population of high-j states via heavy-ion-induced transfer reactions

One of the early hopes of heavy-ion-induced transfer reactions was to populate states not seen easily or at all by other means. To date, however, I believe it is fair to say that spectroscopic studies of previously unknown states have had, at best, limited success. Despite the early demonstration of selectivity with cluster transfer to high-lying states in light nuclei, the study of heavy-ion-induced transfer reactions has emphasized the reaction mechanism. The value of using two of these reactions for spectroscopy of high spin states is demonstrated: /sup 143/Nd(/sup 16/O,/sup 15/O) /sup 144/Nd and /sup 170/Er(/sup 16/O,/sup 15/O..gamma..) /sup 171/Er. (WHK)
Date: January 1, 1982
Creator: Bond, P.D.
Object Type: Article
System: The UNT Digital Library
SIMMER as a safety analysis tool (open access)

SIMMER as a safety analysis tool

SIMMER has been used for numerous applications in fast reactor safety, encompassing both accident and experiment analysis. Recent analyses of transition-phase behavior in potential core disruptive accidents have integrated SIMMER testing with the accident analysis. Results of both the accident analysis and the verification effort are presented as a comprehensive safety analysis program.
Date: January 1, 1982
Creator: Smith, L. L.; Bell, C. R.; Bohl, W. R.; Bott, T. F.; Dearing, J. F. & Luck, L. B.
Object Type: Article
System: The UNT Digital Library
Evidence of former higher temperatures from alteration minerals, Bostic 1-A well, Mountain Home, Idaho (open access)

Evidence of former higher temperatures from alteration minerals, Bostic 1-A well, Mountain Home, Idaho

Cuttings from the silicic volcanics in the Bostic 1-A well near Mountain Home, Idaho have been examined petrographically with the assistance of x-ray diffraction and electron microprobe analyses. Results indicate that these rocks have been subjected to much higher temperatures than were observed in the well in 1974, when a static temperature log was run. It is not known to what extent the alternation may be due to greater depth of burial in the past, or whether it resulted from an early hydrothermal system of higher temperature than the one now observed.
Date: January 1, 1982
Creator: Arney, B.
Object Type: Article
System: The UNT Digital Library
Calculations of thermal-reactor spent-fuel nuclide inventories and comparisons with measurements (open access)

Calculations of thermal-reactor spent-fuel nuclide inventories and comparisons with measurements

Comparisons with integral measurements have demonstrated the accuracy of CINDER codes and libraries in calculating aggregate fission-product properties, including neutron absorption, decay power, and decay spectra. CINDER calculations have, alternatively, been used to supplement measured integral data describing fission-product decay power and decay spectra. Because of the incorporation of the extensive actinide library and the use of ENDF/B-V data, it is desirable to compare the inventory of individual nuclides obtained from tandem EPRI-CELL/CINDER-2 calculations with those determined in documented benchmark inventory measurements of spent reactor fuel. The development of the popular /sup 148/Nd burnup measurement procedure is outlined, and areas of uncertainty in it and lack of clarity in its interpretation are indicated. Six inventory samples of varying quality and completeness are examined. The power histories used in the calculations have been listed for other users.
Date: January 1, 1982
Creator: Wilson, W. B.; LaBauve, R. J. & England, T. R.
Object Type: Article
System: The UNT Digital Library
Acoustic agglomeration of power plant fly ash. Final report (open access)

Acoustic agglomeration of power plant fly ash. Final report

The work has shown that acoustic agglomeration at practical acoustic intensities and frequencies is technically and most likely economically viable. The following studies were performed with the listed results: The physics of acoustic agglomeration is complex particularly at the needed high acoustic intensities in the range of 150 to 160 dB and frequencies in the 2500 Hz range. The analytical model which we developed, although not including nonlinear acoustic efforts, agreed with the trends observed. We concentrated our efforts on clarifying the impact of high acoustic intensities on the generation of turbulence. Results from a special set of tests show that although some acoustically generated turbulence of sorts exists in the 150 to 170 dB range with acoustic streaming present, such turbulence will not be a significant factor in acoustic agglomeration compared to the dominant effect of the acoustic velocities at the fundamental frequency and its harmonics. Studies of the robustness of the agglomerated particles using the Anderson Mark III impactor as the source of the shear stresses on the particles show that the agglomerates should be able to withstand the rigors of flow through commercial cyclones without significant break-up. We designed and developed a 700/sup 0/F tubular agglomerator of …
Date: January 1, 1982
Creator: Reethof, G. & McDaniel, O.H.
Object Type: Report
System: The UNT Digital Library
Aspects of model selection in multivariate analyses (open access)

Aspects of model selection in multivariate analyses

Analysis of data sets that involve large numbers of variables usually entails some type of model fitting and data reduction. In regression problems, a fitted model that is obtained by a selection process can be difficult to evaluate because of optimism induced by the choice mechanism. Problems in areas such as discriminant analysis, calibration, and the like often lead to similar difficulties. The preceeding sections reviewed some of the general ideas behind assessment of regression-type predictors and illustrated how they can be easily incorporated into a standard data analysis.
Date: January 1, 1982
Creator: Picard, R.
Object Type: Article
System: The UNT Digital Library
Interaction of noble-metal fission products with pyrolytic silicon carbide (open access)

Interaction of noble-metal fission products with pyrolytic silicon carbide

Fuel particles for the High-Temperature Gas-Cooled Reactor (HTGR) contain layers of pyrolytic carbon and silicon carbide, which act as a miniature pressure vessel and form the primary fission product barrier. Of the many fission products formed during irradiation, the noble metals are of particular interest because they interact significantly with the SiC layer and their concentrations are somewhat higher in the low-enriched uranium fuels currently under consideration. To study fission product-SiC interactions, particles of UO/sub 2/ or UC/sub 2/ are doped with fission product elements before coating and are then held in a thermal gradient up to several thousand hours. Examination of the SiC coatings by TEM-AEM after annealing shows that silver behaves differently from the palladium group.
Date: January 1, 1982
Creator: Lauf, R. J. & Braski, D. N.
Object Type: Article
System: The UNT Digital Library
Internal magnetic fields in hcp-iron (open access)

Internal magnetic fields in hcp-iron

The magnetic behavior of hcp-Fe (epsilon iron) has been investigated by the Moessbauer Effect over a wide range of temperature T, pressure P, and applied magnetic field H/sub 0/. The internal field H/sub i/ of the induced moment is given by H/sub i/ = 0.20 +- .01 H/sub 0/ and is independent of T and P. Enhanced paramagnetism is suggested as the most likely origin for a contribution of this magnitude to H/sub i/.
Date: January 1, 1982
Creator: Taylor, R. D.; Cort, G. & Willis, J. O.
Object Type: Article
System: The UNT Digital Library
Integrity of PWR pressure vessels during overcooling accidents (open access)

Integrity of PWR pressure vessels during overcooling accidents

The reactor pressure vessel in a pressurized water reactor is normally subjected to temperatures and pressures that preclude propagation of sharp, crack-like defects that might exist in the wall of the vessel. However, there is a class of postulated accidents, referred to as overcooling accidents, that can subject the pressure vessel to severe thermal shock while the pressure is substantial. As a result of such accidents vessels containing high concentrations of copper and nickel, which enhance radiation embrittlement, may possess a potential for extensive propagation of preexistent inner surface flaws prior to the vessel's normal end of life. For the purpose of evaluating this problem a state-of-the-art fracture mechanics model was developed and has been used for conducting parametric analyses and for calculating several recorded PWR transients. Results of the latter analysis indicate that there may be some vessels that have a potential for failure today if subjected to a Rancho Seco (1978) or TMI-2 (1979) type transient. However, the calculational model may be excessively conservative, and this possibility is under investigation.
Date: January 1, 1982
Creator: Cheverton, R.D.; Iskander, S.K. & Whitman, G.D.
Object Type: Article
System: The UNT Digital Library
Light composite fermions: an overview (open access)

Light composite fermions: an overview

Some rules which have been proposed, including 't Hooft's anomaly conditions, decoupling conditions and tumbling versus no tumbling are discussed. Then mass generation mechanisms for composite fermions are covered, including weak gauging, strong gauging, and unification. The origin of the different generations of quarks and leptons is then considered. In the context of composite models, the three generations of quarks and leptons must appear in the first approximation as three sets of massless composite fermions in identical representations of continuous flavor symmetry with a conserved generation number distinguishing them. The generation symmetry is preferably a discrete one in order to avoid massless Goldstone bosons that would occur if one could spontaneously break a continuous symmetry. Harari and Seiberg have shown that in a class of rishon models there exist U(1) generation symmetries that are automatically broken to a discrete generation symmetry due to strong interaction instantons. An example of a solution to the anomaly conditions with this property is given. (GHT)
Date: January 1, 1982
Creator: Raby, S.
Object Type: Article
System: The UNT Digital Library
Clonal theory of radiation carcinogenesis (open access)

Clonal theory of radiation carcinogenesis

In some cases, usually involving high-LET radiations, the dose response at low doses follows a power function of dose with exponent less than one over a wide dose range. This type of response is of great interest since (a) it implies greater effect per unit dose at progressively smaller doses, and (b) it is not predicted by most models and theories of radiobiology. A theoretical framework is presented for responses having the above characteristics over a dose range extending over a factor of 1000. The model postulates precursor cells which occur in clones. Different numbers of precursor cells per clone are assumed. Suitable transformation of a single cell in a clone completes initiation of that clone and raises the probability of tumor formation. At low doses, clones with large numbers of cells at risk have relatively high probability of response. However, depletion of the number of untransformed large clones with increasing dose leaves primarily untransformed smaller clones with smaller probability of response per unit dose. The analytical results demonstrate that power functions with exponent less than one can result even for doses so small that the mean number of charged particle traversals per cell is much less than one. The …
Date: January 1, 1982
Creator: Baum, J.W.
Object Type: Article
System: The UNT Digital Library
Microfaunal evidence of age and depositional environments of the Cerro Prieto section (Plio-Pleistocene), Baja California, Mexico (open access)

Microfaunal evidence of age and depositional environments of the Cerro Prieto section (Plio-Pleistocene), Baja California, Mexico

Microfossils including benthic and planktic foraminifera, ostracodes, calcareous algae, fish skeletal material, and fragments of pelecypods were found in 14 core samples from depths of 185 to 1952 m in the Cerro Prieto geothermal field, providing evidence of both the age and depositional history of sediments comprising the 3000-m-thick Pliocene and Pleistocene section in this area. Ostracodes of brackish water and marine origin constitute the most common microfossils present in this sequence occurring in 8 samples; in situ littoral and neritic species of benthic foraminifera occur in 5 samples with planktic species present in 2 samples. Distributional patterns of ostracodes and foraminifera together with previously analyzed lithofacies (Lyons and van de Kamp, 1980) indicate that the Cerro Prieto section represents an intertonguing complex of alluvial, deltaic, estuarine, and shallow marine environments deposited along the front of the Colorado River delta as it prograded across the Salton Trough during Pliocene and Pleistocene time. Foraminiferal evidence indicates that a sand and shale unit commonly present at depths between 700 and 1100 m represents a significant mid-Pleistocene marine incursion in the Cerro Prieto area. Tentative correlation of the Cerro Prieto section with the well dated Palm Springs Formation of the Imperial Valley, California …
Date: January 1, 1982
Creator: Ingle, J.C. Jr.
Object Type: Report
System: The UNT Digital Library
Electron bremsstrahlung angular-distribution fits for atomic numbers 1 less than or equal to Z less than or equal to 92, and incident-electron energies 1 keV less than or equal to T less than or equal to 500 keV (open access)

Electron bremsstrahlung angular-distribution fits for atomic numbers 1 less than or equal to Z less than or equal to 92, and incident-electron energies 1 keV less than or equal to T less than or equal to 500 keV

The analytic fit of a simple expression to the electron bremsstrahlung angular distribution cross section d/sup 2/sigma/dkd..cap omega.. (differential in the emitted photon energy k and angle ..cap omega..) is investigated. Optimal choices for the fit parameters are determined and fit coefficients are tabulated for a large number of neutral-atom cases. Results are also presented for fits to the relativistic Coulomb-Born approximation. Comparisons between the screened neutral-atom results and the Coulomb-Born results are made. Discrepancies reported to exist between angular distribution cross sections and fit coefficients published by Tseng, Pratt and Lee are confirmed and understood in terms of their choice of fit weight function.
Date: January 1, 1982
Creator: Kissel, L.
Object Type: Report
System: The UNT Digital Library
Shielding considerations for advanced space nuclear reactor systems (open access)

Shielding considerations for advanced space nuclear reactor systems

To meet the anticipated future space power needs, the Los Alamos National Laboratory is developing components for a compact, 100 kW/sub e/-class heat pipe nuclear reactor. The reactor uses uranium dioxide (UO/sub 2/) as its fuel, and is designed to operate around 1500 k. Heat pipes are used to remove thermal energy from the core without the use of pumps or compressors. The reactor heat pipes transfer mal energy to thermoelectric conversion elements that are advanced versions of the converters used on the enormously successful Voyager missions to the outer planets. Advanced versions of this heat pipe reactor could also be used to provide megawatt-level power plants. The paper reviews the status of this advanced heat pipe reactor and explores the radiation environments and shielding requirements for representative manned and unmanned applications.
Date: January 1, 1982
Creator: Angelo, J.P. Jr. & Buden, D.
Object Type: Article
System: The UNT Digital Library
Stochastic modelling of physiologic processes with radiotracers and positron emission tomography (open access)

Stochastic modelling of physiologic processes with radiotracers and positron emission tomography

The compartment model, so often used in nuclear medicine and in pharmacokinetics, is formed by a set of linear differential equations of order one with constant coefficients; its validity depends upon the hypothesis that the system described contains a finite number of components, and that each component is homogeneous. These hypotheses exclude the presence of diffusion and of age-dependent processes, or in general of transport of a non-Markovian nature. The fact that frequently the experimental data agree with this model does not necessarily prove the model is appropriate, but only that it is flexible. In addition to the consistency with the experimental data, an obvious conceptual requirement of the model is that its parameters could be interpreted in terms of perceivable physical properties. All this considered, it will be demonstrated that the experimental data can be examined in terms of a model making a minimum number of assumptions and giving the best physical interpretations to the parameters involved. By way of example, a high resolution positron emission tomograph will be used to determine the successive moments describing the blood circulation through different sections of the brain. Whereever the relative moments form a geometric progression, the circulation in that section follows …
Date: January 1, 1982
Creator: Rescigno, A.; Lambrecht, R. M. & Duncan, C. C.
Object Type: Article
System: The UNT Digital Library