Showing papers by "Argonne National Laboratory published in 1974"
TL;DR: In this article, the authors present a review of channeling and blocking effects in a monocrystalline solid, and some of the applications of these effects, as well as a survey of the published literature.
Abstract: The motion of energetic charged particles inside a monocrystalline solid can be strongly influenced by channeling and blocking effects. The present article reviews the theory, the experimental studies, and some of the applications of these effects. The coverage of the published literature extends through June 1973.
1,204 citations
TL;DR: In this article, the authors discuss in a unified manner configurations of idealized atomic nuclei, rotating liquid drops and rotating idealized astronomical masses with surface tension, and the existence of super-deformed nuclei.
713 citations
TL;DR: In this article, an analysis of the segregation-induced strain field around the voids indicates that minor substitutional alloying elements with negative and positive size factors segregate towards and away from the void surface respectively.
287 citations
TL;DR: In this paper, the short-wavelength collective excitations in liquid rubidium at 320 K have been studied by coherent neutron scattering and clear evidence of propagating modes was found from the shape of the scattering function.
Abstract: The short-wavelength collective excitations in liquid rubidium at 320 K have been studied by coherent neutron scattering. For values of $\ensuremath{\kappa}=\frac{2\ensuremath{\pi}}{\ensuremath{\lambda}}$ up to 1.0 ${\mathrm{\AA{}}}^{\ensuremath{-}1}$, clear evidence of propagating modes was found from the shape of the scattering function $S(\ensuremath{\kappa}, \ensuremath{\omega})$ at constant values of $\ensuremath{\kappa}$. This result shows that the existence of such modes does not depend upon either quantum effects or low thermal population of the modes.
203 citations
TL;DR: In this article, a simple numerical procedure is given for the removal of states with spurious center-of-mass components, which does not require explicit construction of the spurious states and is shown that removal of spurious components signifivantly modifies the 16 O spectrum of Zuker, Buck and McGrory.
200 citations
180 citations
176 citations
174 citations
TL;DR: In this paper, a collection and critical review has been made of the experimental and theoretical data on momentum transfer cross sections for electron collisions with H, He, O, Ne, Ar, Kr, Xe, Cs, Hg, H2, N2, O2, CO, NO, NH3, NH4, and CH4.
162 citations
TL;DR: In this article, the phonon dispersion relation of CdTe at 300 \ifmmode^\circ\else\textdegree\fi{}K has been measured for the [100, [111, and [110] directions of propagation using neutron inelastic scattering.
Abstract: The phonon dispersion relation of CdTe at 300 \ifmmode^\circ\else\textdegree\fi{}K has been measured for the [100], [111], and [110] directions of propagation using neutron inelastic scattering. The CdTe single crystal was grown from the melt with Cd present as $^{114}\mathrm{Cd}$ to reduce the neutron absorption of the specimen. The results have been fitted to a 14-parameter shell model that represents both the neutron data and other measured properties well when the non-neutron data are included in the fit. The present results, along with earlier measurements on $\ensuremath{\alpha}\ensuremath{-}\mathrm{Sn}$ and InSb, complete the isoelectronic sequence $\ensuremath{\alpha}\ensuremath{-}\mathrm{Sn}\ensuremath{\rightarrow}\mathrm{InSb}\ensuremath{\rightarrow}\mathrm{CdTe}$. The systematic trends in the lattice dynamics of this series of semiconductors (which is characterized by increasing band gap and ionicity) are brought out by comparison of frequency distributions calculated from the shell-model fits.
154 citations
TL;DR: In this article, the mean-square acceleration given by molecular-dynamics (MD) calculations on liquid rubidium at 46 \ifmmode^\circ\else\textdegree\fi{}C and 1502 g ${\mathrm{cm}}^{\ensuremath{-}3}$ have been made using a suitable pair potential.
Abstract: Molecular-dynamics (MD) calculations on liquid rubidium at 46 \ifmmode^\circ\else\textdegree\fi{}C and 1502 g ${\mathrm{cm}}^{\ensuremath{-}3}$ have been made using a suitable pair potential Whereas for wave number $\ensuremath{\kappa}l12$ ${\mathrm{\AA{}}}^{\ensuremath{-}1}$ propagating density fluctuations were obtained, only overdamped nonpropagating fluctuations are found for larger $\ensuremath{\kappa}$ For all $\ensuremath{\kappa}$ there is good agreement with recent neutron inelastic-scattering experiments The mean-square acceleration given by MD is found to be much larger than the value derived from another neutron experiment extending over $\ensuremath{\kappa}=4 \mathrm{to} 8$ ${\mathrm{\AA{}}}^{\ensuremath{-}1}$; the reason for the discrepancy is analyzed to show that the neutron-scattering data cannot be interpreted in terms of the mean-square acceleration alone
TL;DR: It is proved that, if S is an unsatisfiable Horn set, there exists a strictly-unit refutation of S employing binary resolution alone, thus eliminating the need for factoring and a theorem similar to Theorem 1 for paramodulation-based inference systems is proven in Theorem 3 but with the inclusion of factoring as an inference rule.
Abstract: The key concepts for this automated theorem-proving paper are those of Horn set and strictly-unit refutation. A Horn set is a set of clauses such that none of its members contains more than one positive literal. A strictly-unit refutation is a proof by contradiction in which no step is justified by applying a rule of inference to a set of clauses all of which contain more than one literal. Horn sets occur in many fields of mathematics such as the theory of groups, rings, Moufang loops, and Henkin models. The usual translation into first-order predicate calculus of the axioms of these and many other fields yields a set of Horn clauses. The striking feature of the Horn property for finite sets of clauses is that its presence or absence can be determined by inspection. Thus, the determination of the applicability of the theorems and procedures of this paper is immediate.In Theorem 1 it is proved that, if S is an unsatisfiable Horn set, there exists a strictly-unit refutation of S employing binary resolution alone, thus eliminating the need for factoring; moreover, one of the immediate ancestors of each step of the refutation is in fact a positive unit clause. A theorem similar to Theorem 1 for paramodulation-based inference systems is proven in Theorem 3 but with the inclusion of factoring as an inference rule. In Section 3 two reduction procedures are discussed. For the first, Chang's splitting, a rule is provided to guide both the choice of clauses and the way in which to split. The second reduction procedure enables one to refute a Horn set by refuting but one of a corresponding family of simpler subproblems.
TL;DR: The size of the total bile acid pool in cholecystectomized patients correlated highly with thesize of the pool of secondary bile acids, suggesting that its apparent return to a normal size in these patients after choleCystectomy could be explained in part by the increased input of secondarybile acids from the intestine.
TL;DR: In this article, a new calibration technique for silicon surface-barrier and other semiconductor detectors to heavy ions is proposed based on the results of measurements of this phenomenon with a variety of ions.
TL;DR: In this article, the authors report neutron-scattering measurements of the coherent scattering function of liquid rubidium at 315 K, in the range of wave vectors $1.25\ensuremath{\le}Q\ENSuremath{-le}5.5$, which indicates at least two characteristic (wavelength-dependent) relaxation times in the liquid.
Abstract: We report neutron-scattering measurements of the coherent scattering function $S(Q,\ensuremath{\omega})$ of liquid rubidium at 315 K, in the range of wave vectors $1.25\ensuremath{\le}Q\ensuremath{\le}5.5$ ${\mathrm{\AA{}}}^{\ensuremath{-}1}$. In this range there is no evidence of peaks at finite $\ensuremath{\omega}$ in $S(Q,\ensuremath{\omega})$ plotted at constant $Q$. On the other hand the Fourier transform $F(Q,t)$ exhibits structure, notably for $Q=2.0$ ${\mathrm{\AA{}}}^{\ensuremath{-}1}$, which indicates at least two characteristic (wavelength-dependent) relaxation times in the liquid. For wave vectors g3.0 ${\mathrm{\AA{}}}^{\ensuremath{-}1}$, $F(Q,t)$ may be characterized by a single relaxation time. These results, in conjunction with our results for $Ql1.0$ ${\mathrm{\AA{}}}^{\ensuremath{-}1}$, offer the possibility of detailed comparisons with models of the liquid state and with molecular-dynamics calculations.
TL;DR: In this article, the density fluctuations in the computer liquid are essentially identical with those in the real liquid as measured by neutron in-elastic-scattering experiments, and the interaction potential used for the simulation should be considered reliable for the study of liquid rubidium.
Abstract: Liquid rubidium has been simulated on a computer. Density fluctuations in the computer liquid are essentially identical with those in the real liquid as measured by neutron in-elastic-scattering experiments. Hence the interaction potential used for the simulation should be considered reliable for the study of liquid rubidium. Density waves are found to propagate even at wavelengths as small as the nearest neighbor distance in the liquid, a property not found in liquid argon.
TL;DR: In this paper, a simple semiclassical model of the reaction process indicates that states of the final nucleus with high spin are greatly favored, while the shell model gives a reasonably complete explanation for the occurence of such high spin states at appropriate excitation energies.
TL;DR: In this paper, a system of 216 water molecules, studied by molecular dynamics at 1 g and 10 g, was found to exhibit a secondary maximum at a much higher frequency than the normal frequency of sound propagation and it was suggested that experiments should be directed to the region of this "high-frequency sound."
Abstract: Fluctuation phenomena occurring in a system of 216 water molecules, studied by molecular dynamics at 1 g ${\mathrm{cm}}^{\ensuremath{-}3}$ and 10 \ifmmode^\circ\else\textdegree\fi{}C, indicate that (i) transverse currents persist in the form of propagating collective coordinates even for a wavelength of about 20 \AA{}, with indications that the same will happen for much longer wavelengths. The velocity of propagation is 1.05 \ifmmode\times\else\texttimes\fi{} ${10}^{5}$ cm ${\mathrm{sec}}^{\ensuremath{-}1}$. In the region of 20 \AA{} the lifetime of the fluctuation appears to increase linearly with increasing wavelength. (ii) Density fluctuations at 20 \AA{} are found to be propagating but only marginally; the corresponding velocity of sound is 1.8 \ifmmode\times\else\texttimes\fi{} ${10}^{5}$ cm ${\mathrm{sec}}^{\ensuremath{-}1}$. (iii) The spectrum of density fluctuations exhibits a secondary maximum at a much higher frequency than the normal frequency of sound propagation and it is suggested that experiments should be directed to the region of this "high-frequency sound."
TL;DR: In this paper, the authors investigated the valence-band structures of thorium, uranium, and their dioxides by means of x-ray photoemission spectroscopy.
Abstract: The valence-band structures of the light actinides thorium, uranium, and their dioxides have been investigated by means of x-ray photoemission spectroscopy. This study shows that the electronic structures of Th${\mathrm{O}}_{2}$ and U${\mathrm{O}}_{2}$ are quite similar, except for the presence of $5f$ electrons in U${\mathrm{O}}_{2}$ which lie close to the Fermi level. It is these low-binding-energy $5f$ electrons that give rise to the most dramatic differences in physical properties, notably the magnetism, electrical conductivity, and color. Conduction in U${\mathrm{O}}_{2}$ apparently occurs via holes created by excitation of rather localized $5f$ electrons from the uranium to interstitial oxygen-acceptor sites. Sputtering experiments on thin oxide film and bulk samples show Fermi-level shifts in x-ray photoemission spectra associated with doping changes that result from preferential removal of interstitial ("impurity") oxygen atoms. The deep-trap and polaron conduction models have been reexamined. It is our view, at this time, that neither model can be ruled out. For the pure metal thorium, valence-band spectra were compared with the available density-of-states calculations and satisfactory agreement was obtained. For $\ensuremath{\alpha}\ensuremath{-}\mathrm{uranium}$, no detailed band calculation exists. However, the results agree with the qualitative density-of-states picture presented by Friedel.
TL;DR: In this article, a shell model with proton configurations (2 p 1 2, 1 g 9 2 ) n was used to find two-body matrix elements fitting to energy levels and transition rates in the N = 50 isotones.
TL;DR: In this article, the authors used a simple and well reproducible crack geometries in copper single-crystals: the crack surfaces are macroscopically plane and the crack front can be forced by appropriate external force distributions into any preselected direction.
TL;DR: In this article, a previously published model of fatigue crack propagation is refined and the resulting slip geometry at the crack tip is calculated, where the slip on both sides of the crack is assumed to occur on slip bands instead of the discrete slip planes used in the old model.
TL;DR: No breaks are induced in the DNA of bacteria irradiated under anaerobic conditions over the dose range tested, and 2‐aminoethylisothiouronium bromide‐HBr protects against break induction in both phage systems.
Abstract: —Irradiation at 365 nm results in the induction of approximately 2–4 times 10-6 and 1-2times 10-6 single-strand breaks (alkali-labile bonds) per 108 daltons per J m-2 in extracted phage T4 DNA and in Escherichia coli bacterial DNA, respectively. The rate of break induction in DNA of intact phage is approximately one-fourth that for extracted phage DNA. 2-aminoethylisothiouronium bromide-HBr protects against break induction in both phage systems. No breaks are induced in the DNA of bacteria irradiated under anaerobic conditions over the dose range tested. Possible induction mechanisms are suggested. Consideration is given to the relative importance of pyrimidine dimers and single-strand breaks in the bactericidal action of 365 nm radiation.
TL;DR: In this article, a physical interpretation of recently obtained sum rules for dielectric functions and for the index of refraction is provided in terms of the inertial properties of the linear Dielectric response of material media.
Abstract: A physical interpretation of recently obtained sum rules for dielectric functions and for the index of refraction is provided in terms of the inertial properties of the linear dielectric response of material media. The superconvergent sum rules are then compared with experimental optical data for AgCl, Al, and Mo and shown to produce good agreement as well as a critical test of extrapolations and of the Kramers-Kronig relations. A straightforward extension to higher powers of the optical constants and their moments is briefly discussed.
TL;DR: In this paper, the ground-state energy of a quantum electron-hole liquid in three cases (i) a single isotropic maximum for the hole band and a single minimum for the conduction band) has been calculated in the random phase (RPA), Hubbard (HA), and fully-self-consistent (FSC) approximations.
Abstract: The ground-state energy of a quantum electron-hole liquid in the three cases (i) a single isotropic maximum for the hole band and a single minimum for the conduction band (called the model system), (ii) Ge under a large [111] strain, and (iii) Si under a large [100] strain, has been calculated in the random-phase (RPA), Hubbard (HA), and fully-self-consistent (FSC) approximations. The last approximation takes into account multiple scatterings to infinite order between all components of the plasma. Effects of anisotropy of bands have also been fully considered. Besides the ground-state energy, we have also calculated the partial-pair-correlation functions and enhancement factors. For the model system, calculations have also been made for different mass ratios. Two important results of this paper are (i) the electron-hole liquid in both Ge and Si under a large uniaxial strain should exhibit a metallic phase relative to a free excitonic phase. The calculated binding energies for Ge[111] and Si[100] are, respectively, 4.9 \ifmmode^\circ\else\textdegree\fi{}K and 21.8 \ifmmode^\circ\else\textdegree\fi{}K, corresponding to equilibrium densities of 1.11 \ifmmode\times\else\texttimes\fi{} ${10}^{16}$ and 4.47 \ifmmode\times\else\texttimes\fi{} ${10}^{17}$ ${\mathrm{cm}}^{\ensuremath{-}3}$. (ii) The enhancement factors at the equilibrium density for Ge[111] and Si[100] are, respectively, 6.8 and 7.4. We suggest that experiments should be done to test these predictions of the FSC theory because of their bearing on the validity of different many-body approximations.
01 Jan 1974
TL;DR: In this article, the authors present an approach to solve the problem of the problem with the use of a set of techniques from the Mechanical Engineering Dept. of Mechanical Engineering, MIT.
Abstract: Massachusetts Institute of Technology. Dept. of Mechanical Engineering. Thesis. 1972. Ph.D.
TL;DR: A comparison of hyperfine coupling constants obtained by electron-nuclear double resonance spectroscopy of in vitro monomer chlorophyll and bacteriochlorophyll free radicals with those of the photoesr signal associated with light conversion in photosynthesis provides convincing support for the special pair model for the in vivo photo-reaction center.
Abstract: A comparison of hyperfine coupling constants obtained by electron-nuclear double resonance spectroscopy of in vitro monomer chlorophyll and bacteriochlorophyll free radicals with those of the photoesr (electron spin resonance) signal associated with light conversion in photosynthesis provides convincing support for the special pair model for the in vivo photo-reaction center.
TL;DR: In this article, the magnetic properties of the neptunium monopnictides, npN, NpP, NnAs, and NpSb have been examined by a variety of experimental techniques, including magnetization, Mossbauer, electrical-resistivity, neutron-diffraction, and lattice-parameter (x-ray) measurements between 1.5 and 300 \ifmmode^\circ\else\textdegree\fi{}K on polycrystalline samples prepared in this laboratory.
Abstract: The magnetic properties of the neptunium monopnictides, NpN, NpP, NpAs, and NpSb, have been examined by a variety of experimental techniques. All compounds have the NaCl structure. The present paper reports the results of magnetization, M\"ossbauer, electrical-resistivity, neutron-diffraction, and lattice-parameter (x-ray) measurements between 1.5 and 300 \ifmmode^\circ\else\textdegree\fi{}K on polycrystalline samples prepared in this laboratory. Particular emphasis is placed on both the complementary information obtained by the different techniques, and how this helps to elucidate the microscopic magnetic behavior. Neptunium nitride is ferromagnetic with ${T}_{C}=87$ \ifmmode^\circ\else\textdegree\fi{}K. Neptunium phosphide orders antiferromagnetically at 130 \ifmmode^\circ\else\textdegree\fi{}K with an incommensurate magnetic structure. At 74 \ifmmode^\circ\else\textdegree\fi{}K the magnetic structure becomes commensurate with the lattice (repeat distance 3.0 unit cells) and at lower temperatures tends to form a 3+, 3- sequence. A complete solution for the magnetic structure at low temperature is obtained by combining the neutron and M\"ossbauer results. Neptunium arsenide becomes antiferromagnetic at ${T}_{N}=175$ \ifmmode^\circ\else\textdegree\fi{}K. At \ensuremath{\sim} 160 \ifmmode^\circ\else\textdegree\fi{}K, the high-temperature 4+, 4- structure transforms to the type-I arrangement (simple +,- sequence). The crystal lattice of NpAs becomes tetragonal at ${T}_{N}$, exhibits a first-order transition to cubic symmetry at 142 \ifmmode^\circ\else\textdegree\fi{}K, and remains cubic at lower temperatures. The electrical resistivity increases by an order of magnitude on cooling from 142 to 141 \ifmmode^\circ\else\textdegree\fi{}K. Neptunium antimonide is a type-I antiferromagnet with ${T}_{N}=207$ \ifmmode^\circ\else\textdegree\fi{}K. The variation of the ordered moments ($\frac{1.4{\ensuremath{\mu}}_{B}}{\mathrm{Np}}$ in NpN to $\frac{2.5{\ensuremath{\mu}}_{B}}{\mathrm{Np}}$ in NpSb), paramagnetic effective moment ($\ensuremath{\sim}\frac{2.5{\ensuremath{\mu}}_{B}}{\mathrm{Np}}$), and the M\"ossbauer parameters (hyperfine field, quadrupole interaction, and isomer shift) all suggest a trend toward ${\mathrm{Np}}^{3+}$, $5{f}^{4}$ free-ion behavior in progressing from the nitride to the antimonide.