bluuebunny/crossref_metadata_2025 huggingface dataset:
Photon cross sections and effective atomic numbers in some alloys
Authors: Reddy D. V. Krishna , Babu K. Suresh , Lingam S. Chandra
Published: April 2011

The total photon cross sections in five nickle-based alloys, viz., Superimphy, Inconel, Nimonic-90, Invar, and stainless steel, are measured at photon energies of 32.1, 52.0, 72.1, 84.3, 145.4, 279.2, 320.0, and 661.6 keV in a good geometric setup using two NaI(Tl) scintillation detectors for low- and medium-energy photons. Experimental total photon cross sections are compared with the theoretical values of Storm and Israel and good agreement is found. Using the subtraction method, we obtain photoelectric and scattering cross sections at appropriate photon energies and compare them with the available theoretical values. The total and partial effective atomic numbers are obtained and presented.
An evaluation of the noise performance of Fe, Co, Si, and B amorphous alloys in ring-core fluxgate magnetometers
Authors: Narod B. B. , Bennest J. R. , Strom-Olsen J. O. , Nezil F. , Dunlap R. A.
Published: April 2011

The work described herein has addressed two questions. Can amorphous metal alloys be used as core material for high-performance fluxgate magnetometers, and do these alloys provide a means for further understanding the noise mechanism(s) of fluxgate magnetometers?We have prepared and studied a suite of fourteen alloys of content (Fe, Co)70, (Si, B)30. Noise levels of the as-cast alloys correlate with coercivity and hysteresis losses and have a local minimum at zero magnetostriction. However, our overall noise minimum coincides with the minimum measured core losses—not at zero magnetostriction.Our best cores perform favourably when compared with the best commercially available Permalloy cores and outperform all cores of the same dimensions that we have examined. Thus we are able to conclude that amorphous metal alloys are a likely source of high-quality material for fluxgate magnetometers.
Section efficace de la réaction Penning pour les atomes
Authors: Gagné J. M. , Bouchard P. , Gleizes A.
Published: April 2011

The average cross section [Formula: see text] for the Penning reaction between Kr (1s5) and [Formula: see text] atoms has been obtained from a comparative study of Kr–U and Kr–Th gas combinations in a hollow-cathode-type generator. The experimental value obtained is 2,8 × 10−15 cm2 ± 50%.
An inverse scattering study of the radiation solution of the Korteweg–de Vries equation: the generic and nongeneric cases
Authors: Enns R. H. , Rangnekar S. S.
Published: April 2011

Although the asymptotic (t → ∞) behaviour of radiation solutions of the Korteweg–de Vries (KdV) equation has been investigated in the literature using the inverse scattering transform method (ISTM), the complete temporal (and spatial) evolution has not been studied in detail using this method. In this paper we discuss the application of the inverse scattering expansion method, a method that we have successfully applied to a wide variety of nonlinear evolution equations of physical interest, to both the generic and nongeneric cases. Using model inputs as illustrative examples, we find that (a) unlike all other problems studied to date, the "natural" expansion parameter is not the (dimensionless) area of the input potential in the direct (eigenvalue) problem, and (b) the value of the reflection coefficient R(k) at zero eigenvalue, i.e., k = 0, plays a crucial role in the success or failure of what we will call the "standard" expansion method. The standard expansion method works for input potentials belonging to the "nongeneric" class, [Formula: see text] but breaks down beyond lowest order in the expansion for potentials belonging to the "generic" class, R(0) = −1. Re-examination of the generic problem in the vicinity of k = 0 leads to a "renormalization" in each order of the expansion, which enables the generic case to be correctly solved. Unlike the nongeneric case, the generic solution is not found to be asymptotically valid.
Near-equalities for some two-dimensional Ising-model correlation ratios
Authors: Frank B. , Nath K.
Published: April 2011

The i–δ relations and the criticality condition, which are used in recent theoretical calculations of the Ising-model transition temperature and critical exponent η, are tested against exact calculations for the two-dimensional lattices: square, plane triangular, and honeycomb. They are found to be valid to within 2%. They are also tested against series results for the three-dimensional hydrogen peroxide lattice, with which they are shown to be consistent to within 3.3%. A new derivation is given of the i–δ relations.
Two-fluid Friedmann–Robertson–Walker cosmologies and their numerical predictions
Authors: Coley A. A. , Tupper B. O. J.
Published: April 2011

Friedmann–Robertson–Walker models satisfying the Einstein field equations for a combination of two fluids, one of which is a comoving perfect fluid with the radiation equation of state [Formula: see text], representing the cosmic microwave background, are discussed. Existing models, in which the second fluid is a comoving perfect fluid, are reviewed and their numerical predictions calculated. These models are generalized by considering the case in which the second fluid is an imperfect fluid. This fluid is necessarily noncomoving, the tilt representing the motion of the local supercluster of galaxies relative to the cosmic microwave background. The numerical predictions of one such model are calculated and are found to be in excellent agreement with observation.
On the transport properties of simple liquids
Authors: Datta S. K.
Published: April 2011

Closed analytical expressions for the diffusion coefficient and shear-viscosity coefficient of dense, simple fluids characterized by the Lennard-Jones potential function have been obtained using the Weeks, Chandler, and Andersen criterion for the division of the pair potential. The expressions are then used to calculate these properties for some real fluids. The deviations between the estimated and measured values of the coefficients are attributed mostly to the approximate nature of the Kirkwood and Rice expressions for shear viscosity and the friction coefficient used to calculate those properties.
Microwave conductivity of p-type InSb at low temperatures
Authors: Poirier M. , Séguin P.-E.
Published: April 2011

A microwave-cavity perturbation technique was used to determine the complex dielectric function [Formula: see text], at 9.5 GHz, of a p-type InSb sample in the 2- to 300-K temperature range. Both the quasi-static and the skin-depth approximations were employed to calculate the ac conductivity on the covered temperature range. At the lowest temperatures, impurity conduction, typical of compensated semiconductors, was found to be ~3 orders of magnitude higher than the dc value. The dielectric constant ε1 ~ 18 was found to be temperature independent.
Superstring physics
Authors: Moffat J. W.
Published: April 2011

The basic features of superstring theory are reviewed with a focus on the cancellation of anomalies in SO(32) and E8 × E8 and the possible finiteness of these theories. The partition function is calculated for the multiloop string amplitudes and analyzed in detail using the functional approach to string quantization.
Gravity, ghosts, and strings
Authors: Mann R. B.
Published: April 2011

A recently introduced technique for extending general relativity is reviewed. This technique, called algebraic extension, yields five theories of gravitation (one of which is Einstein's) that might have interesting implications for strong-field gravitational physics. The particle spectra of these theories are presented. Only one of the four extensions is free of ghosts and tachyons. There exists a (hitherto unexplored) formulation of this theory that contains a gauge-invariant string Lagrangian in the linear approximation.
Muon-induced fission in 235U and 238U
Authors: Ahmad S. , Häusser O. , Macdonald J. A. , Olaniyi B. H. , Olin A. , Beer G. A. , Mason G. R. , Kaplan S. N.
Published: April 2011

Muon-induced prompt and delayed fission yields in 235U and 238U have been measured. A coincidence with the muonic uranium Kα X-rays was used to identify the muon stop in the target. The experimental absolute fission yields per muon stop were 0.142 ± 0.023 for 235U and 0.068 ± 0.013 for 238U. The disappearance rate of muons from the 1s state of muonic uranium has also been measured in the fission mode. Muon-induced fission lifetimes were 71.6 ± 0.6 ns for 235U and 77.2 ± 0.4 ns for 238U. No evidence for a short-lifetime fission – isomer component was found. Comparison of lifetime results with previously measured values in the electron, gamma, and neutron decay modes indicated that the systematic discrepancies could be explained by muon capture on fission fragments produced from prompt fission.
The quantum-mechanical two-level system with dissipation and feedback: application to nonlinear dielectric response
Authors: Grindlay J.
Published: April 2011

A power-series expansion for long-time solutions is obtained for the density-matrix equations of motion describing a quantum-mechanical two-level system with dissipation and feedback. The resonances in the first- and third-order dipole contributions and the second-order upper level occupation probability are shown to be significantly affected by the feedback.The results are applied to the case of a uniformly polarized, finite, crystalline dielectric made up of two-level systems. Polarizabilities relating the dipole moment to each of the applied field, the internal field, and the macroscopic field are introduced and relations between them derived. The dipole-moment – macroscopic-field polarizabilities are shown in particular to be shape independent. Susceptibilities are defined and related to the single-system polarizabilities through generalized Clausius–Mossotti relations.
Charged matter and a one-parameter group of conformal motions: II
Authors: Krori K. D. , Borgohain P. , Das Kanika , Sarma Arunima
Published: April 2011

We present in this paper some illustrative applications of the solutions derived in the preceding paper for spherical distributions of charged matter under a one-parameter group of conformal motions. One of the applications is of some astrophysical significance.
Plasma waves in laser fusion plasmas
Authors: Baldis H. A. , Villeneuve D. M. , Walsh C. J.
Published: April 2011

This paper presents a review of plasma wave generation in laser-produced plasmas. A general review is given of stimulated scattering phenomena and the use of Thomson scattering techniques to diagnose waves in plasma. Two examples of the application of such methods are given: one is the simultaneous measurement of plasma and ion waves produced by the two-plasmon decay instability, the other the observation of plasma waves generated by stimulated Raman scattering.
Prospects for an accurate measurement of the branching ratio π0 → e+e−/π0 → all
Authors: Waltham C. E.
Published: April 2011

The π0 → e+e− branching ratio has been the subject of two recent measurements, each with quoted errors of ± 35% or greater. The results are mutually consistent but 3–4 times larger than any conventional theory can accommodate. Outlined in this paper is a method that can potentially achieve an unambiguous measurement accurate to ± 5% by normalization to a well-understood internal-conversion process.
Intensités absolues des transitions de vibration–rotation des bandes ν2 et ν4 du méthane 12CH4
Authors: Loete M. , Hilico J. C. , Qasri M. B.
Published: April 2011

The general expansion of the transformed dipole moment of tetrahedral XY4 molecules, considered by Loete, is used to study the line strengths of the ν2 and ν4 bands of methane, 12CH4. This systematic expansion, written in tensorial form in the Td group, considers all the interactions to a given order and, contrary to the polynomial methods, it allows an accurate interpretation of the strength perturbations. The two bands ν2 and ν4 have been chosen to show the possibilities of the model. They have been studied separately, and then in interaction. In each case, the experimental precision has been obtained for both strong and weak lines. The isolated band scheme requires two and five parameters for the ν2 and ν4 bands respectively, while three parameters are sufficient in the dyad scheme.
The excitation of O(1S) and O2 bands in the nightglow: a brief review and preview
Authors: McDade I. C. , Llewellyn E. J.
Published: April 2011

Recent laboratory and in situ studies of the processes involved in the excitation of O(1S) and the five strongest systems of molecular oxygen in the terrestrial nightglow are reviewed. In spite of the significant advances that have been made during the last few years, it is not yet possible to reconcile rocket and satellite photometric observations with expectations based on laboratory kinetic data. Even in the most extensively studied O2 system, the Herzberg-I system, serious discrepancies exist between the kinetic parameters measured in the laboratory and those deduced from the airglow observations. It is only in the case of the O2 Atmospheric system that the laboratory and in situ studies have converged on a consistent view of the overall excitation mechanism. In the case of the O(1S) green line, most evidence would now appear to support the Barth mechanism, but progress towards a conclusive identification of the Barth precursor state, or states, is seriously hindered by the inadequacies in current understanding of the molecular oxygen systems.
Vibrational excitation in
Authors: Slanger Tom G.
Published: April 2011

Excitation processes for [Formula: see text] in aurorae, in the nightglow, and in laboratory sources are discussed. It is shown that the observed vibrational distribution in aurorae is consistent with the [Formula: see text] + NO charge-transfer mechanism. Arguments are presented for the case that quenching of O2(b) in vibrational levels above ν′ = 1 is rapid, and that therefore the auroral source is much larger than previously supposed. It is suggested that oxygen atoms are an efficient quencher for O2(b) levels above ν′ = 1.
Complex formation in solid deuterium in the presence of a ion
Authors: Bose S. K. , Poll J. D.
Published: April 2011

Using the Metropolis scheme, we have carried out a Monte Carlo simulation of solid deuterium in the neighbourhood of a [Formula: see text] ion. The simulation is performed using a [Formula: see text] potential, which is based on the theoretical study of the stationary-point geometries of [Formula: see text] conformers by Yamaguchi et al. Complexes similar to [Formula: see text] clusters, as observed in the supersonic nozzle-beam experiments of van Deursen and Reuss, are found to form in the solid. Infrared absorption in solid deuterium due to the presence of such complexes is discussed.
Étude paramétrique du plasma produit par un arc stabilisé par un champ magnétique axial
Authors: Abel G. , Bélanger C. , Boivin R. , Charette E. , Gregory B. C.
Published: April 2011

An arc stabilized using an axial magnetic field is produced in low-pressure helium by discharging a delay line between two metal electrodes. Several diagnostic techniques are used to measure the characteristics of the arc. The parameters of the cylindrical plasma are as follows: pulse length 2 ms, length 0.227 m, radius 0.03 m, electron density 4 × 1020 m−3, electron temperature ≤ 60 eV, ion temperature ≤ 20 eV. The arc is a rich source of vacuum-ultraviolet line radiation coming from multiply charged impurity ions. Based on a choice of typical parameters, we present a simple self-consistent model to explain the observed phenomena.
Potential-energy curves, zero-field splittings, and radiative lifetimes for low-lying states of AsH
Authors: Matsushita Toshio , Marian Christel M. , Klotz Rainer , Peyerimhoff Sigrid D.
Published: April 2011

Large-scale multireference configuration-interaction (MRD-CI) calculations in an atomic-orbital (AO) basis set containing up to f functions on As and d on hydrogen are employed to study the potential-energy curves of the π2(X3Σ−, a1Δ, b1Σ+), the σ → π, and the π → σ3.1Π states; a large number of σ → σ* states; and the lowest π → s,p Rydberg series. The σ → σ* states are strongly repulsive and exhibit numerous interactions with the Rydberg members causing predissociation. The probabilities for the spin-forbidden transitions from b1Σ+and a1Δ to the X3Σ−ground state as well as the zero-field splittings of theX3Σ−and A3Π states have been evaluated by employing a variational perturbation scheme in which the zero-order wave functions are MRD-CI expansions. The perturber states are determined by their spin-orbit interactions, which are calculated by employing the Breit–Pauli one- and two-electron spin-orbit operator. The radiative lifetime of the b1Σ+ state is predicted to be 0.35 ms, whereby the dominant mechanism is deactivation to the ms = ±1 component.The parallel transition is found to be much weaker. The lifetime of a1Δ is calculated to be 22 ms, whereby the process [Formula: see text] is favored. Both b–X and a–X transitions borrow their intensity primarily from the A3Π–X3Σ− transition and, furthermore, the 1Π–a1Δ and higher 3,1Π state spin-allowed transitions. The probability for the quadrupole b–a transition is evaluated to be three orders of magnitude smaller than the b–X transition. The calculated zero-field splitting of the X3Σ− ground state amounts to 101.4 cm−1, and the fine-structure splitting between the 2, 1, and 0+ components of the A3Π state evaluated to be 544.5 and 674.4 cm−1, respectively, in good accord with experimental results; whereas the calculated Λ doubling of the0+–0− fine-structure levels of the A3Π state (35.2 cm−1 vs. 44.72 cm−1) is too small in the present treatment. The dependence of spin-orbit effects and transition probabilities on AO basis sets and relativistic corrections to the zero-order Hamiltonian are discussed, and it is concluded that lifetime calculations for spin-forbidden processes in first- and second-row molecules can be extended in a fairly straightforward manner to systems with considerable spin-orbit interactions.
Dissipative systems: on the natural inclusion of radiation loss in the quantized electromagnetic field
Authors: Baseia B. , Feitosa F. J. B. , Liberato A.
Published: April 2011

The inclusion of damping in the quantized radiation field in pure and mixed states is accomplished in a natural way, without using traditional loss reservoirs, through the application of appropriate boundary conditions in a simple model of an optical cavity coupled to the outside world. By using collective operators (which are suitable weighted superpositions of the usual creation and annihilation operators for modes of the continuous spectrum, extended over each Fox–Li band) and convenient initial conditions, we are able to describe the radiation loss from an optical cavity to the outside world. The physical situations corresponding to initial conditions leading to the exponential damping are also investigated.
On the linear response of Bardeen–Cooper–Schrieffer superconductors II: superconducting alloys
Authors: Cleary Robert
Published: April 2011

The linear response to longitudinal modulations in a superconducting alloy is calculated for the general case. Extension to transverse waves, point-charge Coulomb potentials, and magnetic dipoles is trivial. All the results are limited to Born approximation, s-wave scattering by the impurities embedded in the superconductor. Derivation of the equations for linear response is the same as for clean superconductors, with the appearing correlation functions containing impurity-averaged vertex parts. Only one vertex part is evaluated here; the remaining ones are easy extensions of our calculation.
The variational approach to the Glashow–Weinberg–Salam model
Authors: Manka R. , Sladkowski J.
Published: April 2011

The variational approach to the Glashow–Weinberg–Salam model, based on canonical quantization, is presented. It is shown that taking into consideration the Becchi–Rouet–Stora symmetry leads to the correct, temperature-dependent, effective potential. This generalization of the Weinberg–Coleman potential leads to a phase transition of the first kind.
Ionospheric electron-content measurements during the second space-plasma negative-ion experiment (SPINEX-2)
Authors: Fulford J. A. , MacDougall J. W. , Forsyth P. A. , Mendillo M. , Bernhardt P. A.
Published: April 2011

The second space-plasma negative-ion experiment (SPINEX-2), a chemical-release active experiment to investigate negative-ion effects in the ionospheric F region, is described by Mendillo et al. This paper describes the electron-content measurements in somewhat more detail than would be appropriate there. The circumstances of the experiment, particularly the use of a vehicle with a very high spin rate, presented some unusual challenges during interpretation of the electron-content data. These are described. The resulting profiles show clearly that the chemical release caused a very significant "hole" in the ionosphere. Under certain fairly realistic assumptions, the actual number of free electrons removed from the region of the peak of the ionospheric F layer is estimated to be about 4 × 1025. The same assumptions lead to a simple radial distribution of the depleted region about the rocket trajectory in the neighborhood of the release.
Gauge-field quantization
Authors: Skinner Ray , Reding Dale F. , Steinke Kim , Wood W. Robert
Published: April 2011

The quantization of gauge fields by means of the Dirac–Bergmann Hamiltonian constraint formulation for generalized dynamical systems is criticized. This formulation is shown to be inconsistent with its implicit assumption that all variables are to be varied in Hamilton's principle and is overly restrictive when applied to simple models. It is shown that the Dirac–Bergmann formulation involves an unjustified assumption in addition to the natural assumption that the gauge field is dynamical. An alternative formulation that does not involve the unjustified assumption is proposed. In this, every variable whose time development is not determined by the equations of motion is treated as a reference, rather than a dynamical, variable and not varied in the action. The proposed formulation is applied to some simple examples, including electromagnetism.
The quantum-mechanical two-level system with dissipation and feedback: multimode applied electric-field case
Authors: Grindlay J.
Published: April 2011

A two-level dissipative quantum-mechanical system subjected to a small applied multimode electric field plus a feedback term proportional to the induced dipole moment is discussed. The long-term behaviour of the induced dipole moment and of the upper level occupation probability is represented by a series expansion in terms of the applied electric-field amplitudes. First-order and third-order internal, external, and intrinsic polarizabilites are introduced and calculated for the model. Certain ratios of third-order to first-order polarizabilities are shown to have a common value for the internal, external, and intrinsic cases. Clausius–Mossotti relations for the linear and third-order susceptibilities are derived.
Zero-temperature properties of quantum spin models on the triangular lattice III: the Heisenberg antiferromagnet
Authors: Fujiki S.
Published: April 2011

The calculation of two- and four-spin correlations of the [Formula: see text] Heisenberg antiferromagnet has been extended to an N = 21 site triangular lattice. The infinite-lattice ground state energy per bond is estimated to be E0/3NJ = −0.3678 ± 0.005 by fitting a quadratic in 1/N to the finite N data. The plaquette chirality order is slightly greater than in the XY antiferromagnet. The two-spin correlation is conjectured to decay as [Formula: see text].
Aperture-field uniformity and cross-polarization level of dual parabolic cylindrical reflectors
Authors: Sanad M. S. A. , Shafai L.
Published: April 2011

For dual parabolic cylindrical reflectors, the field distribution over the aperture is calculated. This aperture-field distribution is a function of the feed orientation, and feed radiation pattern, the feed polarization, and the geometry of the configuration, in particular, the focal lengths of the two reflectors and the angle between them. The effects of these parameters on the uniformity of the co-polar component and the level of the cross-polar component of the aperture field are studied, and some representative results are presented. It is shown that by a proper selection of the geometrical parameters of the system, a high degree of co-polar field uniformity on the aperture can be maintained. Therefore, the system can be used as a compact antenna range to test large antennas.
Sum rules for isovector excitations
Authors: Macfarlane M. H.
Published: April 2011

This paper deals with the sum rules obtained from the energy moments of multipole-excitation strength functions. An explicit expression in terms of ground-state orbit-occupation probabilities is given for the total, non-energy-weighted strength of isovector excitations. For the Gamow–Teller (GT) excitation, separate sum rules are obtained for the total (p, n) and (n, p) strengths; these sum rules satisfy the Ikeda relation (S(p, n)–S(n, p) = 3(N – Z)) exactly. The GT sum rules are then used to estimate the influence of ground-state correlations on total (p, n) and (n, p) strengths in 208Pb. Sizeable strength enhancements are obtained, ranging from around 15% (in units of 3(N – Z) for longer range random-phase approximation correlations to 50% or more if short-range nuclear-matter correlations are included. An assessment is then given of the current status of the problem of missing Gamow–Teller strength in heavy nuclei. Brief concluding sections deal with the isospin splitting of isovector excitations and further development of the energy–moment sum rules.
Gamow–Teller strength function for 90Zr(n,p)90Y
Authors: Bloom S. D. , Mathews G. J. , Becker J. A.
Published: April 2011

The Gamow–Teller (GT) strength function for90Zr → 90Y has been calculated in a model space including two-particle two-hole excitations from the 2p shell to the 1g9/2 shell. Our purpose here is to eventually compare this with the latest results from the 90Zr(n,p)90Y TRIUMF experiment at 0°, which should be available soon. Our calculations (as a function of the amount of ground-state correlations) predict rather similar shapes and regions of excitation but grossly different magnitudes for the total GT strength. In the case of 90Zr → 90Y, the GT transition is forbidden in zero order. Therefore, ground-state correlations must be well understood before the degree and sources for Gamow–Teller quenching can be known.
A diode-laser study of the ν4 band of CD3Br
Authors: Paso R. , Kyrö E. , Anttila R.
Published: April 2011

The ν4 band of CD3Br around 2300 cm−1 was studied under Doppler-limited resolution by using a diode-laser spectrometer. Altogether, more than 600 lines belonging to the sub-bands [Formula: see text] were observed for both the isotopic species CD379Br and CD381Br. In the analysis, the Coriolis resonance between ν4 and ν3 + ν5 + ν6(E) was taken into account.
Electrical and optical properties of vacuum-deposited amorphous Zn3P2 thin films
Authors: Arsenault C. J. , Brodie D. E.
Published: April 2011

Amorphous Zn3P2 thin films were prepared by vacuum deposition. Reproducible electrical and optical properties were obtained by annealing the samples in the same way immediately after the deposition. Conductivity and thermopower measurements were performed and explained using the Mott and Davis model, and a long-range potential fluctuation suggested by Overhof and Beyer.
Magneto gas dynamic singular surfaces in an isothermal flow of gas
Authors: Ojha S. N. , Singh Ashok
Published: April 2011

The discontinuity surfaces across which the only discontinuities in the derivatives of flow variables exist are known as singular surfaces. The influence of a magnetic field on the propagation of singular surfaces in an isothermal flow of gas is investigated. We find that the expansive waves ultimately disperse while compressive waves grow into a shockwave in a finite time. The derivation of the shock-wave formation time and its dependence on the magnetic-field intensity reveal interesting differences between outward- and inward-moving singular surfaces. In the particular cases of plane and cylindrical singular surfaces, the shock-wave formation distances and times have been derived.
Deterioration of the high-temperature oxide superconductor in various ambient environments
Authors: Morrish A. H. , Zhou X. Z. , Raudsepp M. , Maartense I. , Eaton J. A. , Luo Y. L.
Published: April 2011

The high-temperature superconductor, YBa2Cu3O7−x, deteriorates when exposed to aqueous and acidic vapors and solutions; these changes are clearly evident in ac susceptibility measurements. Decomposition products are determined by X-ray diffraction.
Differential cross sections for the competing charge-transfer reactions Kr+(2P3/2) + Kr(1S0) → Kr(1S0) + Kr+(2P3/2) and Kr+(2P3/2) + Kr(1S0) → Kr(1S0) + Kr+(2P1/2)
Authors: Howard Stephen L. , Rockwood Alan L. , Trafton Walter , Friedrich Bretislav , Anderson Stephen G. , Futrell Jean H.
Published: April 2011

The crossed-beam method was used to investigate the charge-transfer reaction of Kr+(2P3/2) with Kr at collision energies of 9.2 and 19.9 eV. A weak plasma ion source was used to generate a nearly pure Kr+(2P3/2) beam. The purity of the beam was tested by using CH4 as a probe reaction; because Kr+(2P3/2) generates [Formula: see text] and Kr+(2P1/2) generates [Formula: see text], the ratio, [Formula: see text], could be used to evaluate the spin-state composition of the reactant ion beam.The resonant reaction occurs via a process well described by a rectilinear-trajectory impact-parameter model proceeding via a [Formula: see text], intermediate in which the electron "hole" is shared equally by both partners. Also evident is the endoergic fine-structure reaction with ΔJ = −1. At 9.2 eV, the endothermic-channel product is scattered at a definite angle, suggesting a short-range interaction that selects a particular impact parameter. At the higher energy investigated, the fine-structure splitting is also evident once the data are deconvoluted. However, the scattering angle is reduced to near zero, corresponding to nearly rectilinear tragectories for both channels at this energy. The population of both channels is in general accord with accepted theories for ion–atom charge exchange, but the energy range at which it is observed is far removed from that predicted (we observe nearly equal cross sections for both channels at energies three orders of magnitude lower than those predicted by theory).
Analysis of auroral first negative bands
Authors: Henriksen K. , Veseth L.
Published: April 2011

An exact numerical approach is used to compute the rotational part of the line strengths (Hönl–London factors) for the [Formula: see text], [Formula: see text] transition (1NG bands). The computed Hönl–London factors enable a synthetic spectrum to be derived, which is then fitted as a final step to observed auroral [Formula: see text] 1NG bands by use of a least squares method. In this way we determine the population densities of the vibrational levels of the upper [Formula: see text] electronic state and, in addition, an average rotational temperature. Our results give clear evidence that the auroral [Formula: see text] 1NG bands are mainly generated by particle impact on neutral O2 molecules in their electronic and vibrational ground states, and that the bands are produced within the E region.
Observations on the B1Π state of the NaK molecule
Authors: Barrow R. F. , Clements R. M. , Derouard J. , Sadeghi N. , Effantin C. , d'Incan J. , Ross A. J.
Published: April 2011

The lowest 1Π state of the NaK molecule, B(1) 1Π, which dissociates to Na (2S1/2) + K (2P3/2), has been studied in three ways: (i) by laser-induced fluorescence recorded at high resolution by Fourier-transform spectrometry, (ii) by dye-laser excitation spectroscopy, and (iii) by observations of the effect of an electric field, which mixes the e and f parity levels of the B1Π state. The B state is subject to numerous small perturbations, many of which arise from interactions with a triplet state, c3Σ+, and these interactions modify the extent of e–f mixing and thus the relative intensities of R and P lines on one hand and the Q lines on the other. These observations of the Stark effect enable perturbation maxima to be located and thus allow relatively unperturbed energy levels to be identified. Constants from these levels of B1Π have been determined from a weighted least squares fit to 1776 lines of the B1Π – X1Σ+ transition as follows:[Formula: see text]
The c3Π – b3Σ+ transition of CO near 8245 cm−1
Authors: Dabrowski I. , Vervloet M. , Wang D.-C.
Published: April 2011

A transition between two high-lying electronic states of CO, c3Π – b3Σ+, has been observed by high resolution Fourier transform spectroscopy, in the near infrared, around 8245 cm−1. The triplet splittings of both c3Π and b3Σ+ have clearly been observed. The value A = 1.504(12) cm−1 has been determined for c3Π and confirms the previous direct determination of Klopotek and Vidal (J. Opt. Soc. Am. B, 2, 869 (1985)). Because these states were found to be heavily perturbed, only the analysis and effective rotational constants are reported.
Magnetic coercivity
Authors: Gaunt Paul
Published: April 2011

The theory of magnetic hardening and its impact on the design of permanent magnets is presented. The statistical theory of domain-wall pinning by sample inhomogeneities is outlined, and its relevance to the latest generation of permanent magnets is discussed.
Theoretical aspects of magnon–magnon interactions in Heisenberg ferromagnets
Authors: Loly P. D.
Published: April 2011

Spin-wave interactions in ferromagnetic insulators have a well-established theoretical foundation, in contrast to the situation for antiferromagnets. These interactions may be classified into two groups according to whether the dominant aspects are of one- or two-magnon character. The weak interactions between spin waves excited at low temperatures are responsible for the success of "free" (or noninteracting) spin-wave calculations in explaining low-temperature thermodynamic properties. In contrast, the two-magnon aspects appear in connection with two-magnon Raman scattering, where pairs of magnons are created in close proximity and consequently interact strongly. Parallels with analogous systems, especially antiferromagnetic spin waves and phonons, are noted in reviewing the ferromagnetic case. Emphasis is placed on the structure of the theory, rather than on the wealth of experimental activity.
The anapole moment and singlet fields
Authors: Czyż H. , Zralek M.
Published: April 2011

We found that the definitions of the static properties of charged leptons within the Glashow–Salem–Weinberg model are equivalent in both the singlet fields and the Rξ gauge fields, at least in the one-loop approximation.
Effect of ground conductivity on the secondary field of a horizontal current-carrying loop
Authors: Helaly A. , Shafai L.
Published: April 2011

The radiation field of a circular loop carrying an electric current and located horizontally above a lossy ground is formulated using the dyadic Green's functions. The resulting field vectors are then split into the primary and secondary components. The primary components represent those that would exist in the absence of the ground, leaving the secondary components to represent the contribution of the Earth. For different frequencies and various ground conductivities, the secondary components are determined and compared with the primary ones. The results indicate that in the vicinity of the loop, both within and outside the ground, the secondary fields are small at low frequencies and may be neglected. This provides a simplifying approximation to handle the return response of buried objects, excited by a circular loop located in the air.
The canonical structure of Podolsky generalized electrodynamics
Authors: Galvão Carlos A. P. , Pimentel B. M.
Published: April 2011

The generalized electrodynamics proposed by Podolsky is analyzed from the Hamiltonian point of view, using Dirac theory for constrained systems. The problem of gauge fixing for the theory is studied in detail and the correct generalization of the radiation gauge is obtained, a subject that has not been examined correctly in the earlier literature. The Dirac brackets for the dynamical variables in this gauge are calculated.
Parity nonconservation in the nucleon–nucleon system: nuclear structure issues
Authors: Haxton W. C.
Published: April 2011

I discuss some of the nuclear structure issues that arise in nuclear tests of parity nonconservation.
Measurement of parity violation in the photodisintegration of deuterium and in the production of bremsstrahlung on tantalum
Authors: Earle E. D. , McDonald A. B. , Kidner S. H. , Clifford E. T. H. , Hill J. J. , Keech G. H. , Chupp T. E. , Schneider M. B.
Published: April 2011

The circular polarization dependent component of the total cross section for photodisintegration of deuterium has been measured: (2.7 ± 2.8) × 10−6 for bremsstrahlung with an end point of 4.1 MeV and (7.7 ± 5.3) × 10−6 for an end point of 3.2 MeV. The helicity-dependent component of the total cross section for the production of bremsstrahlung on tantalum by longitudinally polarized electrons has been measured: (0.63 ± 0.70) × 10−6 for an electron energy of 4.1 MeV and (3.1 ± 1.5) × 10−6 at 3.2 MeV. All measurements are in agreement with theoretical predictions for these processes.
Raman scattering from sputtered films of YBa2Cu3Oy
Authors: Chrzanowski J. , Irwin J. C. , Parsons R. R. , Mulhern P. J.
Published: April 2011

Thin films of the high-temperature superconductor YBa2Cu3Oy have been deposited on Al2O3 and MgO substrates by dc magnetron sputtering. Raman-scattering experiments have been carried out on these films at various temperatures. The results of these experiments have been used to estimate the amount of impurity phases in the films, to characterize the actual superconducting films, and to test for any preferential orientation within the film. Vibrational modes of the superconductor were found at 148, 226, and 338 cm−1 in both sets of films, at 446 and 491 cm−1 in the Al2O3 films, and at 441 and 500 cm−1 in the MgO films. The measured frequencies of the highest energy modes have been used to determine the oxygen content of the films.
Some remarks on electron scattering in a laser field
Authors: Ehlotzky F.
Published: April 2011

Potential scattering of electrons in a quantized radiation field is reconsidered. Some remarks are made on the validity of the Kroll–Watson scattering formula and on the close connection of this formula with the classical transition rate of scattering in a radiation field.
A high average-power quasi-continuous optical parametric oscillator system
Authors: Thewalt M. L. W. , Beckett D. J. S.
Published: April 2011

A quasi-continuous, widely and rapidly tunable optical parametric oscillator (OPO) with high average power is described. A Cu-vapour laser pumped, tunable dye laser has been used to pump a LiNbO3 OPO at a repetition rate of 6 kHz. Rapidly tunable infrared radiation in the range of 0.83–2.42 μm has been obtained with average powers as high as 136 mW in the short-wavelength branch of the output.
The submillimetre laser: industrial applications
Authors: Bergeron Michel , Bernard Pierre , Boulay Russell , Drouin Bernard , Gagnon Richard
Published: April 2011

This report describes experiments aimed at demonstrating the potential of the submillimetre laser in the field of nondestructive material testing. Most of the research has concentrated on paper properties, such as sheet density, moisture content, and fibre orientation, but other materials have also been tested. The results show that this type of laser is very well suited to the measurement of various physical properties of dielectric sheet materials.
Energy levels of 94Nb populated directly via the (n, γ) reaction
Authors: Kennett T. J. , Prestwich W. V. , Tsai J. S.
Published: April 2011

The 93Nb(n, γ)94Nb reaction has been used to explore the level structure of 94Nb to an excitation energy of 3900 keV. Although selection rules for this reaction do limit the states that can be directly populated, in this case the rich resonance structure and the p-wave strength enhance the number of possibilities. The present study, for which exceedingly high statistical precision has been attained, reveals a total of 334 transitions that if assumed to be of a primary nature, can be directly associated with levels. The neutron separation energy, based upon the mass scale via the 14N(n, γ)15N reaction, is found to be 7227.51 ± 0.09 keV. This is significantly lower than the currently accepted value of 7229.5 ± 0.5 keV. While the energies of low-lying states are found to have values in agreement with those deduced using the most recent crystal spectrometer measurements, significant deviations are observed for levels above 900 keV. The completeness of the study has permitted examination of statistical nuclear properties, such as the energy dependence of the level density and the photon transition strength.
Measurements of the low-temperature electrical resistivity of sintered silver powders by acoustic propagation in high magnetic fields
Authors: Guillon F.
Published: April 2011

Measurements of the electrical resistivity of sintered-silver submicrometre powders by an acoustic method are reported. The monotonic increase of the ultrasonic attenuation in a high magnetic field at 4.2 K follows the behaviour predicted by the Alpher and Rubin model of impure solid metals. Data taken at 10 and 30 MHz have allowed us to determine the residual resistivity ρ in the order of 1.9 μΩ-cm for a sintered sample with a 50% packing factor. Furthermore, analysis of the acoustic attenuation suggests a contribution depending on the dimensions and geometry of both the sample and ultrasonic transducer.
Charge-induced absorption in proton-beam-irradiated solid hydrogen deuteride
Authors: Miller J. J. , Brooks R. L. , Hunt J. L. , Poll J. D.
Published: April 2011

The charge-induced absorption spectrum in the fundamental band of solid hydrogen deuteride irradiated by a beam of 15 MeV protons has been observed. Four charge-induced absorption lines were seen, including one due to a small hydrogen impurity in the sample. Two of the three HD lines are caused by electron bubbles in the solid. These lines have been named Q1(0)− and S1(0)−, indicating the parent transition and the sign of the perturbing charge. Under higher resolution, the third line, named Q1(0)+, shows a doublet structure. The possibility that this doublet structure is caused by [Formula: see text] cluster ions is examined. A comparison of the timing and temperature dependence of the charge-induced lines in HD is made with previous results in D2.
Complete fluorescence spectrum of a normal and atherosclerotic aorta
Authors: Bergeron A. , Douville Y. , Duplain G.
Published: April 2011

The use of lasers to ablate atherosclerotic plaque has proved promising. To achieve safe conditions of laser angioplasty, researchers have proposed different methods for accurate localization of plaque. Research has been done on the use of induced fluorescence in distinguishing normal arteries from affected ones. In the present study, an entire fluorescence spectrum (excitation–emission) from 200 to 1000 nm has been done on normal and affected arteries. Previous studies on the fluorescence spectroscopy of arterial walls have generally been done at discrete excitation wavelengths. Our study shows that the entire fluorescence spectrum gives a more accurate diagnosis.
Cross section and linear polarization of tagged photons
Authors: Asai J. , Caplan H. S. , Skopik D. M. , Bianco W. Del , Maximon L. C.
Published: April 2011

Formulae for bremsstrahlung cross sections and polarizations are usually presented in coordinate systems not very suitable for application by experimental physicists to devices such as photon-tagging monochromators. In this paper the transformations between the different coordinate systems are presented, along with examples of the calculated cross sections and polarizations in a form convenient from the experimental standpoint. These examples also give the predicted characteristics of the photon tagger currently under construction at the Saskatchewan Accelerator Laboratory.
Mass scale dependence in operator regularization
Authors: McKeon D. G. C.
Published: April 2011

We investigate the role of the mass scale parameter μ2 that naturally arises in the course of computing radiative corrections in quantum-field theory when using operator regularization. When dealing with renormalizable theories, a change in the value of μ2 can be compensated for by a change in the physical parameters that characterize the theory, and a set of renormalization group equations similar to those of Gell-Mann and Low are derived. As operator regularization does not give rise to divergences at any stage of a calculation, it is possible to compute radiative corrections in so-called nonrenormalizable interactions. In these theories, a change in the physical parameters of the theory cannot compensate for a change in the value of μ2; rather, μ2 is fixed by the strength of effective interactions generated by radiative processes. Finally, we suggest that even in renormalizable theories, the value of μ2 is determined by a mechanism for mass generation, suggested by Nambu and Jona-Lasinio.
Finitely conducting orthogonal magnetohydrodynamic plane flows
Authors: Chandna O. P. , Barron R. M. , Chew K. T.
Published: April 2011

Flows with straight streamlines and flows with streamlines as the involutes of a curve are investigated. The solutions for the resulting flow problems are obtained for finitely conducting, steady plane orthogonal viscous magnetohydrodynamic flows.
Integrated absorption coefficients of W(ΔJ = 6) transitions in solid hydrogen and the sixty-fourth multipole moment of H2
Authors: Balasubramanian T. K. , D'souza R. , D'Cunha Romola , Rao K. Narahari
Published: April 2011

Theoretical expressions are derived for the absorption intensities of the zero-phonon Wν←0(0), Wν←0(1) single transitions and Wν←0(0) + Qν′←0(0) double transitions in solid hydrogen. From a comparison with available experimental data, the tetra-hexacontapole (64th pole) moment of the hydrogen molecule is estimated to be 0.25 [Formula: see text].
Characteristics of clusters produced in nucleon–nucleus interactions at ultrahigh energies
Authors: Goyal D. P. , Kumar Animesh , Singh K. Yugindro , Singh S.
Published: April 2011

The phenomenon of cluster production in nucleon–nucleus interactions at ultrahigh energies [Formula: see text] has been investigated using the available cosmic-ray data. The rapidity gap distributions of charged particles in a nondiffractive region of the cross section are found to support the Snider two-channel model as opposed to the model of Quigg, Pirilla, and Thomas. The variation of cluster density and cluster size with the primary energy, multiplicity of shower particles, and nature of the target mass has also been studied.
Are Z = 2 anomalons fractionally charged projectile nuclei?
Authors: Ghosh Dipak , Roy Jaya , Sarkar Sharmila
Published: April 2011

This paper reports a preliminary study on the measurement of the charge of projectile fragments having [Formula: see text] in extreme peripheral interactions of C12 with emulsions at 4.5 GeV ∙ c−1 ∙ n−1. This study was done to determine if Z = 2 anomalons are third integral fractionally charged nuclei. This method of charge measurement is based on the determination of lacunarity and estimates the charge of relativistic projectile fragments (PFs) with a standard deviation of [Formula: see text]. No evidence for the existence of fractionally charged PF has been found, and possible implications are discussed.