Showing papers by "Argonne National Laboratory published in 1972"
TL;DR: In this paper, a modification of an earlier theory of Singwi et al of electron correlations at metallic densities is presented, which allows for the change of the pair correlation function in an external weak field via the density derivative of the equilibrium pair correlation functions.
Abstract: In this paper we present a modification of an earlier theory of Singwi et al of electron correlations at metallic densities The modification consists in allowing for the change of the pair correlation function in an external weak field via the density derivative of the equilibrium pair correlation function This results in a new expression for the local-field correction The present theory has the merit of satisfying almost exactly the compressibility sum rule and of giving a satisfactory pair correlation function Results of self-consistent numerical calculations for the static pair correlation function, correlation energy, compressibility, and plasmon dispersion relation for the electron liquid in the metallic-density range are presented For those interested in the application of the results of the present paper, numerical values of the local-field correction as a function of wave number have been tabulated in the density range ${r}_{s}=1\ensuremath{-}6$
732 citations
16 May 1972
TL;DR: The 'feel' of an interactive system can be compared to the impressions generated by a piece of music, which will seem, after a few listenings, to be so natural the observer wonders why it was never done before.
Abstract: The 'feel' of an interactive system can be compared to the impressions generated by a piece of music. Both can only be experienced over a period of time. With either, the user must abstract the structure of the system from a sequence of details. Each may have a quality of 'naturalness' because successive actions follow a logically self-consistent pattern. Finally, a good composer can write a new pattern which will seem, after a few listenings, to be so natural the observer wonders why it was never done before.
224 citations
TL;DR: In this article, the Bethe asymptotic formula involving two parameters that represent important atomic properties has been used to describe the energy dependence of the measured cross sections of ionization cross sections.
Abstract: Ionization cross sections of forty gases have been measured for electrons of kinetic energies 0.1-2.7 MeV. The measurements are absolute and extensive precautions have been taken to minimize systematic and accidental errors. The energy dependence of the measured cross sections is accurately described by the Bethe asymptotic formula involving two parameters that represent important atomic properties. Comparisons have been made between ${\mathrm{H}}_{2}$ and ${\mathrm{D}}_{2}$ and between C${\mathrm{H}}_{4}$ and C${\mathrm{D}}_{4}$; the observed differences are of the order of 1% and too small to be resolved with certainty. A close comparison has been made between positrons and electrons in Ar at 0.67 and 1.1 MeV; the cross sections are observed to be equal within a probable error of 0.5%.
199 citations
TL;DR: The Murchison meteorite contains aliphatic and aromatic hydrocarbons similar to those made in static Fischer-Tropsch-type syntheses as discussed by the authors, which can account for most principal features of meteorite organic matter.
187 citations
TL;DR: In this article, a systematic procedure for the derivation of sum rules for the optical constants of material media from dispersion relations, in analogy with superconvergence techniques of high-energy physics, is given.
Abstract: A systematic procedure is given for the derivation of sum rules for the optical constants of material media from dispersion relations, in analogy with superconvergence techniques of high-energy physics. In addition to the well-known $f$-sum rules, a number of new sum rules are obtained for the refractive index, the dielectric tensor, and its inverse. In particular, it is shown that the average value of the real refractive index over the whole frequency spectrum is equal to unity. The physical implications of the new results are discussed in connection with the dispersion of optical constants, with the effect of external perturbations, and with the theory of natural optical activity.
166 citations
TL;DR: In this paper, the authors review the experimental status of identifiable centrifugal-barrier effects in: (i) shapes of resonances, (ii) accounts for deviations in SU(2) and SU(3) predictions for ratios between partial decay widths, and (iii) accounting for the dependence on spin of the elastic widths of the resonances lying on the same Regge trajectory.
Abstract: (1) We review the experimental status of identifiable centrifugal-barrier effects in: (i) shapes of resonances, (ii) accounting for deviations in SU(2) and SU(3) predictions for ratios between partial decay widths, and (iii) accounting for the dependence on spin of the elastic widths of resonances lying on the same Regge trajectory. (2) We present a contour plot from which the "kinematic partial width" (centrifugal-barrier penetration factor times two-body phase space) of any resonance into any decay channel may be obtained immediately, given the orbital angular momentum, semiclassical impact parameter, and an assumed strong-interaction radius. Using this technique we display, as an example, the kinematically preferred decays of the high-spin mesons on the leading meson trajectory (assumed linear). (3) We obtain an approximate lower bound on the strong-interaction radius on the basis of general considerations. (4) We show that, for high-spin resonances, it can be expected that the mass enhancements in different decay channels associated with these resonances may be shifted by a half-width or so with respect to each other, because of different centrifugal-barrier effects in the different channels. (5) We also show that production cross sections of high-spin particles on leading linear trajectories by either formation or peripheral processes will be substantially suppressed by centrifugal-barrier effects. (6) Finally, we observe that the production cross sections and decay widths of mesons on the leading trajectory of the Veneziano model can be understood almost entirely on the basis of kinematical considerations if the radius of the region in which the decay particles interact strongly grows linearly with the mass of the decaying resonance.
150 citations
TL;DR: In this paper, the inelastic-scattering functions for liquid argon have been measured at 85.2 K. The data, which are presented as smooth scattering functions at constant values of the wave-vector transfer in the range 1.0-4.4
Abstract: The inelastic-scattering functions for liquid argon have been measured at 85.2 K. The coherent-scattering function was obtained from a measurement on pure ${\mathrm{A}}^{36}$ and the incoherent-scattering function was derived from the result obtained from the ${\mathrm{A}}^{36}$ sample and the result obtained from a mixture of ${\mathrm{A}}^{36}$ and ${\mathrm{A}}^{40}$ for which the scattering is predominantly incoherent. The data, which are presented as smooth scattering functions at constant values of the wave-vector transfer in the range 1.0-4.4 ${\mathrm{\AA{}}}^{\ensuremath{-}1}$, are corrected for multiple-scattering contributions and for resolution effects. Such corrections are shown to be essential in the derivation of reliable scattering functions from neutron-scattering data. The incoherent-scattering function is compared to recent molecular-dynamics results and the mean-square displacement as a function of time is derived. The coherent-scattering function is compared to molecular-dynamics results and also, briefly, to some recent theoretical models.
148 citations
TL;DR: In this paper, the isotopic composition of atmospheric CO in the northern hemisphere has been studied and the most likely nature of these sources is discussed and the production rates estimated. But the isotope pattern is different from that for CO from automobile engine combustion, whether compared to combustion in the same region as the air sample or to an estimated world average.
122 citations
TL;DR: In this paper, a momentum-space method is developed for the calculation of three-body terms in the Brueckner-Bethe method for nuclear matter, which is similar to one used earlier for central $S$-wave potentials.
Abstract: A momentum-space method is developed for the calculation of three-body terms in the Brueckner-Bethe method for nuclear matter. The method is similar to one used earlier for central $S$-wave potentials. Here we extend it to the full nuclear force, including tensor forces, spin-orbit forces, etc. Furthermore, we show how the method can be used to investigate the possibility of long-range correlations in nuclear matter by summing the generalized ring series. The numerical accuracy obtainable with various mesh parameters and cut-offs in momentum space, and with various truncations of partial-wave expansions, is thoroughly explored. Several angle-average approximations are used, and the estimated numerical accuracy in the three-body cluster energy is 10-15%. The method is applied to a central potential ${v}_{2}$, a semirealistic potential ${v}_{6}$ (Reid), which has a tensor force, and to the Reid potential, augmented by an interaction that is consistent with empirical scattering phase shifts in two-body partial waves with $j\ensuremath{\ge}3$. In all cases the three-body contribution to the energy is correctly given in order of magnitude by ${\ensuremath{\kappa}}_{2}{D}_{2}$, where ${D}_{2}$ is the two-body contribution and ${\ensuremath{\kappa}}_{2}$ is the usual convergence parameter of the Brueckner-Bethe method. The generalized ring series is found to converge rapidly, indicating that long-range correlations are not very important for the binding energy of nuclear matter. The Reid potential is found to saturate at the right energy but at too high a density.NUCLEAR STRUCTURE Method for solving Brueckner-Bethe three-body equations in nuclear matter developed and applied to the Reid potential.
119 citations
TL;DR: From 2728 events of 205-GeV $ √ p √ n interactions found in 15,000 pictures taken with the 30-in. hydrogen bubble chamber at the National Accelerator Laboratory, a total cross section of 39.1 mb was measured.
Abstract: From 2728 events of 205-GeV $\mathrm{pp}$ interactions found in 15 000 pictures taken with the 30-in. hydrogen bubble chamber at the National Accelerator Laboratory, a total cross section of 39.5\ifmmode\pm\else\textpm\fi{}1.1 mb was measured. The mean charged-particle multiplicity for inelastic $\mathrm{pp}$ collisions was measured to be 7.65\ifmmode\pm\else\textpm\fi{}0.17. The prong distribution from 2 to 22 prongs is broader than a Poisson distribution and has a width parameter $f_{2}^{}{}_{}{}^{\ensuremath{-}}=〈{n}_{\ensuremath{-}}({n}_{\ensuremath{-}}\ensuremath{-}1)〉\ensuremath{-}{〈{n}_{\ensuremath{-}}〉}^{2}=0.95\ifmmode\pm\else\textpm\fi{}0.21$.
114 citations
TL;DR: In this article, a mathematical model is proposed to describe the phenomena of parallel-flow-induced vibrations of a flexible rod, and a solution is obtained for a rod with arbitrary end conditions; the solution can be used for fixed, hinged, cantilevered and other elastically supported end conditions.
TL;DR: In this article, the temperature and volume dependences of the lattice vibrational frequencies are revealed, and it is concluded that the large increase in γ(αv) at low temperatures cannot be attributed to a large temperature dependence of (∂C′/∂P)T.
TL;DR: In this paper, the authors studied the diffusion of hydrogen in a single crystal of palladium (Pd${\mathrm{H}}_{0.03}$) by quasielastic neutron scattering.
Abstract: The diffusion of hydrogen in a single crystal of palladium (Pd${\mathrm{H}}_{0.03}$) has been studied by quasielastic neutron scattering. The results provide the best evidence yet obtained for the applicability of a simple jump model of hydrogen diffusion in a metal and confirm the predominant occupation of octahedral sites in the Pd crystal, with a mean residence time at 623 K of 2.8 psec between jumps.
TL;DR: In this paper, a review of the work of the author and his co-workers in the field of conductivity measurements on pulse-irradiated aqueous solutions is presented.
TL;DR: In this article, the problem of applying fracture mechanics to the opening mode fracture of a two-material (aluminum-epoxy-aluminum) system is investigated, and the relationship between the homo geneous system and the adhesive system for both K and g is obtained.
Abstract: This study investigates the problem of applying fracture mechanics to the opening mode fracture of a two-material (aluminum-epoxy-aluminum) system. The results of a finite element analysis of a two-material, single- edge-notch (SEN) plate are used with a compliance method in order to obtain strain energy rates, g, and with a displacement method to obtain stress intensity factors, K. Approximate relationships between the homo geneous system and the adhesive system for both K and g are determined. The relationship between K and g for the adhesive system is obtained. The experimental investigation provides an experimental compliance calibration for the same adhesive system and loading. Good reproducibility of the fracture toughness values obtained for the two-material system with SEN and tapered DCB specimens indicates the geometry independence of the fracture toughness. The effect of the notch root radius and proper specimen preparation are also considered.
TL;DR: Energy production by fast breeding remains the main goal of the Liquid Metal Fast Reactor (LMFR) to ensure a sustainable long term fissile fuel supply and the recycling of the Minor Actinides content of nuclear waste burning them to produce energy and reduce the amounts of disposed waste.
Abstract: Energy production by fast breeding remains the main goal of the Liquid Metal Fast Reactor (LMFR) to ensure a sustainable long term fissile fuel supply. In addition, the use of LMFRs allows the recycling of the Minor Actinides content of nuclear waste burning them to produce energy and reduce the amounts of disposed waste. Another advantage of the LMFR is its higher thermal efficiency compared with water-cooled reactors. The sustainable, environmentally clean long term use of nuclear power can be achieved with fast reactors, since thermal reactors are capable of burning less than 1 percent of the uranium fuel. It is surmised that the known reserves of uranium will fuel thermal reactors for only a few decades. Fast reactors burn most of the uranium fuel extending the power producing capability of the uranium reserves into the hundreds of years, making the recoverable energy resource from uranium larger than from coal.
TL;DR: In this paper, the anomalous behavior of the resistivities of Pu and Np and some actinide intermetallic compounds can be explained on the basis of spin fluctuations in narrow $5f$ bands.
Abstract: It is proposed that the anomalous behavior of the resistivities of Pu and Np and some actinide intermetallic compounds can be explained on the basis of spin fluctuations in narrow $5f$ bands. An initial ${T}^{2}$ increase is observed in the resistivities of all these systems. From radiation-damage data we conclude that there are two distinct regions of $5f$-electron behavior: (i) a high-temperature region (\ensuremath{\gtrsim} 100 \ifmmode^\circ\else\textdegree\fi{}K), where the $5f$ electrons occupy virtual bound states and the metal resembles a disordered alloy with magnetic impurities such as Pd(U), and (ii) a low-temperature region, where the $5f$ bands are hybridized and a well-defined Fermi surface is formed. Anomalies observed in several properties of Pu at 60 \ifmmode^\circ\else\textdegree\fi{}K may well reflect the temperature at which well-defined $5f$ bands begin to form.
TL;DR: RNase and alkaline digests of the mit[ 3 H]valyl-tRNA-mit-DNA hybrid yielded [ 3 H ]valyladenosine and [ 3H]valine, respectively, providing further evidence for the validity of the hybridization system.
TL;DR: The intrastream ecological preferences of these sympatric catostomids suggest that the hemoglobins without the Bohr effect confer an ecological advantage in a swift water habitat.
Abstract: The oxygen equilibria of Catostomus insignis hemoglobins are p H dependent. Catostomus clarkii hemoglobins have some components (20 percent) whose oxygen equilibria are independent of p H because the alpha chains have NH 2 -termini that are blocked and the beta chains lack the "usual" COOH-terminal histidine. Since the Bohr effect is normally a beneficial phenomenon, the maintenance of some hemoglobins without a Bohr effect must provide a physiological advantage that is habitat specific. The intrastream ecological preferences of these sympatric catostomids suggest that the hemoglobins without the Bohr effect confer an ecological advantage in a swift water habitat.
TL;DR: In this article, the authors measured the grain boundary self-diffusion coefficient in silver using the sectioning technique, for polycrystals, 〈100〉 16° tilt bicrystals, and à à 18 à 14 à 15 à 16 à 17 à 19 à 20 à 21 à 22 à 23 à 24 à 25 à 26 à 27 à 28 à 30 à 31 à 34 à 35 à 36 à 38 à 40 à 41 à 42
TL;DR: A possible role for the cathodal hemoglobins in helping to maintain intrastream niche segregation of sympatric catostomid species is proposed.
TL;DR: The residual resistivity increase rate as a function of induced resistivity for fast neutron irradiated Al, Cu, Ag, Au, Pt, Fe, Ni, Co and Mo has been studied as discussed by the authors.
Abstract: The residual resistivity increase rate as a function of induced resistivity for fast neutron irradiated Al, Cu, Ag, Au, Pt, Fe, Ni, Co and Mo has been studied. Except for Fe the resistivity increase rate as a function of irradiation induced resistivity is non-linear. The data is best explained with the expression of Balarin and Hauser. Saturation values of the resistivity and defect concentrations plus static and dynamic recombination volumes have been calculated; they differ from those obtained by irradiation in a reactor spectrum. Recombination volumes are very small for the b.c.c. metals Fe and Mo.
Die Anstiegsrate des Restwiderstands als Funktion des induzierten Widerstands wurde an mit schnellen Neutronen bestrahltem Al, Cu, Ag, Au, Pt, Fe, Ni, Co und untersucht. Ausber fur Fe ist die Anstiegsrate des Widerstands als Funktion des strahlungsinduzierten Widerstands nichtlinear. Die Werte am besten mit dem Ausdruck von Balarin und Hauser beschrieben. Sattigungswerte des Widerstands und der Defektkonzentration, wie statische und dynamische Rekombinationsvolumina, wurden berechnet; sie unterscheiden sich von denen, die durch Bestrahlung im Reaktor erhalten wurden. Die Rekombinationsvolumina sind fur die k.r.z. Metalle Fe und Mo sehr klein.
TL;DR: Absorption spectra in the visible and infrared have been recorded for films of dry chlorophyll a, chlorophylla b, bacteriochlorophyll, pyrochlorophylla a, and pheophytin a and it is possible to deduce structures for the chlorophyLL species involved and to correlate the visible absorption spectra of both chlorophyller oligomers and chlorophyllers-water adducts with particular chlorophylli species.
TL;DR: In this article, the naphthalene energy-loss spectrum from 3 to 16 eV obtained for 100 eV incident electrons closely resembles photo-absoprtion results and the need to include Rydberg configurations for any theoretical analysis of the spectrum is emphasized.
TL;DR: A variety of nitrogen compounds have been synthesized by a static Fischer-Tropsch type reaction from CO, D2 and ND3, with Ni-Fe and Al2O3 catalysts.
TL;DR: In this paper, a comparison of the characteristics of the mass distribution for low-energy fission of nuclides ranging from −227 to −256 fission was given, and the average masses of the light and heavy groups were 111.9 and 141.0, respectively.
Abstract: The distribution of mass in the spontaneous fission of $^{256}\mathrm{Fm}$ has been investigated by the radiochemical determination of the fission yields for 28 mass chains. The mass distribution is asymmetric with a peak-to-valley ratio of \ensuremath{\sim}12. The average masses of the light and heavy groups are 111.9 and 141.0, respectively. The fission-yield data indicate a value of 3 \ifmmode\pm\else\textpm\fi{} 1 for $\overline{\ensuremath{
u}}$, the average number of neutrons emitted per fission. A comparison of the characteristics of the mass distribution for low-energy fission of nuclides ranging from $^{227}\mathrm{Th}$ to $^{256}\mathrm{Fm}$ is given.
TL;DR: LIFE-II as mentioned in this paper provides a detailed thermal, radiation, and mechanical analysis of cylindrical fast-reactor fuel-element behavior as a function of actual reactor operating history.
TL;DR: Gap equations for the N = Z doubly even nuclei in the s-d shell with the Yale t-matrix were derived in this article, which showed that α-α correlations can create coherent potentials.
TL;DR: In this paper, it was shown that the total cross sections for two-and three-photon ionization of a one-electron atom depend on the polarization of the incident light.
Abstract: We present a theoretical interpretation of an effect recently observed in two- and three-photon ionization of Cs. We show that the total cross sections for two- and three-photon ionization of a one-electron atom depend on the polarization of the incident light. Expressions are derived for the ratio of the cross section for circularly polarized light to that for linearly polarized, and their maximum values are obtained.