bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of negative parity levels in 63Cu
Authors: Kulkarni R.G. , Navalkele D. P.
Published: April 2011

Low-lying negative parity levels in 63Cu were Coulomb excited with 3.25 to 4.25 MeV protons to test the weak coupling core-excitation model. A Ge(Li) detector was used to measure the gamma-ray yields. The 1412, 1547, and 1861 keV levels in 63Cu were Coulomb excited for the first time. Gamma-ray angular distributions were measured at 4.25 MeV proton energy in deducing multipole mixing ratios and spin values. The E2 and M1 reduced transition probabilities were determined for the six states. The 669.6, 962, 1327, and 1547 keV levels have properties consistent with the interpretation of coupling a 2p3/2 proton to the first 2+core state. The present results were compared with the available particle–core and particle–phonon model calculations.
A study of bound multineutron system
Authors: Mehrotra I.
Published: April 2011

The possibility of existence of a bound multineutron system consisting of 8 and 20 neutrons has been analysed theoretically. It is observed that the realistic interactions do not bind these systems. However, a suitable effective interaction can produce bound states.
Special points for two-dimensional Brillouin zone or Wigner–Seitz cell integrations
Authors: Chow H. C. , Vosko S. H.
Published: April 2011

Various methods of generating special point formulae for two–dimensional Brillouin zone or Wigner–Seitz cell integrations, useful for the calculation of surface properties, are compared. The direct solution of the coupled non-linear transcendental equations, which determine the special points and their weights, by means of a least squares method is found to be feasible for small numbers of sample points and yields the most efficient formulae. For large numbers of sample points the product Gauss–Chebychev method is most practical.
Laser-induced fluorescence and discharge emission spectra of CrO. Rotational analysis of the A5Π–X5Π transition
Authors: Hocking W. H. , Merer A. J. , Milton D. J. , Jones W. E. , Krishnamurty G.
Published: April 2011

The A5Π–X5Π electronic transition of CrO, near 6000 Å, has been analysed in detail using laser-induced fluorescence and conventional discharge emission spectroscopy. The transition provides the first instance where it has been possible to analyse the rotational structures of quintet electronic states completely. Although the parallel polarization of the transition has prevented the spin–orbit coupling and Λ-doubling intervals from being observed directly, it is shown that sufficient indirect information exists in the spectrum for them to be obtained with fair precision. The excited state, A5Π, is perturbed by large numbers of other electronic states which have no intensity of their own for emission to the ground state. The analysis of the perturbed regions has been greatly facilitated by the laser-induced fluorescence spectra: the excitation spectra correspond to a rotational temperature close to room temperature (which offers a significant improvement in resolution over the discharge spectra), and the J-assignments of the perturbed lines given by the resolved fluorescence spectra are unambigious
High resolution rotation–vibration Raman spectra of acetylene. I. The spectrum of C2H2
Authors: Kostyk E. , Welsh H. L.
Published: April 2011

The Raman spectrum of gaseous acetylene was excited in a multiple-reflection Raman cell by a single-moded Ar+ laser and recorded photographically; the gas pressure was 380 Torr and the spectral slit-width ~0.1 cm−1. The three Raman-active fundamentals ν1, ν2, and ν41 of C2H2 were analyzed to give the band origin, ν0, and the upper state constants, B1 and D1; accurate infrared values of the lower state constants, B0 and D0, were assumed in the analysis. The values of the constants for the ν2 band illustrate the accuracy obtained: ν0 = 1974.317(2), B1 = 1.170419(14), D1 = 1.579(18) × 10−6 cm−1. Five difference bands originating in transitions from the low-lying ν4 = 1 and ν5 = 1 vibrational states were also measured and analyzed.
Cancellation in the transition integrals for some dipole transitions: He isoelectronic series
Authors: Ghoshal Swadesh Kumar , Sengupta Sankar
Published: April 2011

The amount of cancellation in the transition integrals for some np–n′d and nd–n′f singlet and triplet transitions for some members of helium isoelectronic sequence is estimated with Hartree–Fock wave functions. The results may act as a measure of the confidence level that can be attributed to the values of oscillator strengths of the respective cases.
The frequency and damping of ion-acoustic waves
Authors: Barnard A. J. , Gulizia C.
Published: April 2011

The dispersion relation for a plasma with different ion and electron temperatures is solved numerically to obtain the frequency and the damping constant for ion-acoustic waves as a function of the wavenumber. It is shown that the commonly used expressions for these variables only apply if the parameter T = ziTe/Ti is larger than 20, and can lead to large errors if T is close to 1. (Here z1 is the ion charge, Te is the electron temperature, and Ti the ion temperature.) Tables and graphs of the frequency and damping as functions of the wavenumber are given for different values of T.
Theoretical models for quasi-two-dimensional mesomorphic monolayers and membrane bilayers
Authors: Caillé A. , Pink D. , Verteuil F. De , Zuckermann M. J.
Published: April 2011

Simple models are developed for the first-order (main) gel–fluid phase transition in lipid mono-and bilayers. The lipid chains are assumed to lie on a triangular lattice in both phases and to interact via anisotropic van der Waals forces. The article begins with a review of previous experimental and theoretical work. Next a two-state Ising-like model is developed and shown to give a good qualitative description of the main phase transition of both mono- and bilayers and of statistical fluctuations about this transition. The article continues with a description of a more quantitative 10-state model for the main bilayer phase transition due to Pink. The polar head interactions are now explicitly taken into account. It is shown that this model is able to account for a variety of experimental results, e.g., Raman scattering data for pure lipid bilayers, phase separations for mixed lipid systems, and ionic permeability data for bilayers. The 10-state model is then extended to include the presence of intrinsic molecules (i.e., cholesterol, anaesthetics, and proteins) dissolved in lipid bilayers. The phase diagrams with their corresponding phase separation regions, the heat of transition, and in some cases the correlations are calculated for such mixed systems using several values of the parameters for the interactions. The penultimate section contains an analysis of the partitioning of anaesthetics between bilayers and the surrounding aqueous medium and its effect on the main phase transition. The article concludes with a discussion of the theoretical results and a summary of recent work.
On solving directly the Griffin–Hill–Wheeler equation for scattering problems
Authors: Onsi M. , Tourneux J. Le
Published: April 2011

We investigate a method for solving the Griffin–Hill–Wheeler equation, in which the generator coordinate amplitudes are approximated by regular functions. The method is applied to elastic α–α scattering and the results are compared with those yielded by other methods. Particular attention is paid to the calculation of physical wave functions free of spurious components.
Rotational and hyperfine structure in the A6Σ+–X6Σ+ electronic transition of MnO
Authors: Gordon R. M. , Merer A. J.
Published: April 2011

The (0,0), (0,1), and (1,0) bands of the A6Σ+–X6Σ+ transition of MnO near 5500 Å have been photographed at high dispersion, and partial rotational analyses carried out. The spectrum is unusually complicated because of the high electron multiplicity, the manganese hyperfine structure, and extensive rotational perturbations. It is found that hyperfine perturbations frequently accompany the rotational perturbations. These are a new type of perturbation, resulting from a mixing of the F3 and F4 electron spin components in the upper state through hyperfine matrix elements of the type ΔN = 0, ΔJ ± 1, ΔF = 0 as a result of rotational perturbations. Extra lines, obeying the selection rules ΔJ = 0, ± 2, are induced: these give the energy separations of the F3 and F4 electron spin components of the ground state. As a result it has been possible to determine the electron spin fine structure parameters for the two states despite the parallel polarization of the electronic transition. The reason for the great complexity of the A6Σ+ ν = 0 level is the occurrence of a large avoided crossing near N = 26 with a level which is possibly a highly excited vibrational level of the ground state. The ground state Mn—O bond length is r0 = 1.6477 Å, and ΔG1/2(X6Σ+) = 832.41 cm−1.
Relativistic electrodynamics of dissipative elastic media
Authors: Kranyš Miroslav
Published: April 2011

A phenomenological general relativistic electrodynamics is proposed for a dissipative elastic solid which is polarizable and magnetizable and whose governing equations form a hyperbolic system. Non-stationary transport equations are proposed for dissipative fluxes (and constitutive equations of electrodynamics) containing new cross-effect terms, as required for compatibility with an entropy principle expressed by a new balance equation (including a new Gibbs equation). The dynamic equations are deduced from the unified Minkowski–Abraham–Eckart energy-momentum tensor. The theory, formed by a set of 29 (reducible to 23) partial differential equations (in special relativity) governing the material behaviour of the system characterized by generalizing the constitutive equations of quasineutral media, together with Maxwell's equations, may be referred to as the electrodynamics of dissipative elastic media (or fluid). The proposed transport laws for polarization and magnetization generalize the well-known Debye law for relaxation and show the influence of shear and bulk viscosity on polarization and magnetization. Besides the form of the entropy function, the free energy function in the non-stationary régime is also formulated.
Rotational and vibrational analysis of the CaF B2Σ+–X2Σ+ system
Authors: Dulick Michael , Bernath Peter F. , Field Robert W.
Published: April 2011

A rotation–vibration analysis of the CaFB2S+–X2Σ+ system is reported. Excitation spectra of CaF are recorded with a cw, 1 MHz bandwidth, dye laser combined with restricted-bandpass (2 Å) fluorescence detection. The accuracy of line measurements is 0.003 cm−1. Nine bands in the Δν = 0 sequence are analyzed (ν″ = 0–2,8,9, 12–15) and selected lines in four Δν = −1 bands (ν″ = 1–4) are used to obtain band origins needed for the vibrational analysis. The main constants (1σ error in parentheses) for the CaF B2Σ+ state are: Te = 18 841.309(3) cm−1. Be = 0.342604(7) cm−1, ωe = 572.405(36) cm−1, αe = 0.002630(6) cm−1, ωexe = 3.143(13) cm−1, Re = 1.955 Å. The B2Σ+ state is found to be in pure precession with A2Π with l = 1.
Electron transport properties of InP
Authors: Lee H. J. , Basinski J. , Juravel L. Y. , Woolley J. C.
Published: April 2011

Measurements of electrical conductivity σ and Hall coefficient RH have been made as a function of temperature in the range room temperature to 250 °C and as a function of magnetic field up to 3.2 T on single crystal n-type samples of InP with carrier concentrations in the range 3.5 × 1021 to 1.2 × 1024 m−3. Theoretical calculations of σ and RH have been made using the method of Fletcher and Butcher and the resulting values fitted to the experimental data by using various scattering parameters as adjustable. The parameters so obtained have then been used to predict further magnetoresistance values and values of thermoelectric power and Nernst–Ettingshausen coefficient. The predicted values of magnetoresistance and thermoelectric power show good agreement with experimental values but not those of the Nernst–Ettingshausen coefficient, possibly due to experimental problems.
Pion structure in a modified quark loop model
Authors: Kim J. H. , Resnick L.
Published: April 2011

The pion is assumed as usual to couple to the electroweak currents through its constituent quarks. The bound state nature of the [Formula: see text] system coupling to the electroweak currents is simulated by a form factor at the [Formula: see text] vertex, parametrized by an effective mass M and coupling strength f. Calculations are performed at the one loop level, with a prescription used to ensure electromagnetic gauge invariance. Isospin invariance is assumed. f, M, and the effective quark mass m are determined by the normalization condition for the pion electromagnetic form factor and the charged and neutral pion lifetimes. The charge radius of the pion is calculated and found to be in good agreement with experiment. The ratio of the axial to vector structure functions in the radiative weak decay π → evγ is also determined.
Pion PT distribution in hadron–nucleus interaction at accelerator energy
Authors: Ghosh Dipak C.
Published: April 2011

In the present work we have investigated the nature of the low PT distribution of secondary charged pions produced in p–nucleus collision in emulsion at the incident beam momentum 22.6 GeV/c. The general characteristics of the PT2 distribution have been found to be the same as in the case of hadron–hadron collisions. A comparison of the PT2 distribution for the two sets of reactions p – heavy nucleus (Nh > 6) and p – light (Nh ≤ 6) is also made.
Rapidity distribution in hadron–nucleus interactions in emulsion at 22.8, 50, 400, and
Authors: Mozumder A. , Goyal D. P. , Sengupta P. K. , Singh S.
Published: April 2011

Rapidity distributions in hadron–nucleus interactions in nuclear emulsion for energies 22.8, 50, 400, and [Formula: see text] are presented. The dependence of rapidity distributions on incident energy and the target mass number (A) has been investigated. The results favour multiperipheral models based on Glauber–Gribov multiple scattering theory.
Governor model for asymmetric deformed nuclei
Authors: Bishara B. A. , Habeeb M. A. Z. , Hadi A. A.
Published: April 2011

The governor model is extended to include the asymmetric shape of nuclei which allows a simultaneous analysis of the data for both the ground state and the γ-vibrational bands in deformed even–even nuclei. The rotationally invariant core is assumed to be a spheroid with an axis of symmetry parallel to the axis of rotation. The calculations are carried out under the assumption of no stretching. The static γ-deformation results are compared with the VMI(ARM) and Krutov values, and the calculated energies are in good agreement with the experimental data.
Design and calibration of a source and a polarimeter for polarized 14.4 keV Mössbauer gamma rays
Authors: Daniels J. M. , Lam H. Y. , Li P. L.
Published: April 2011

A source of polarized 14.4 keV Mössbauer γ rays, using a magnetized foil, and a polarizer using a single crystal of siderite, are described. The procedures for determining the polarization of the γ rays, and for calibrating and using the polarimeter, are described in detail.
The determination of band masses and deformation potentials in white tin from an orthogonalized plane wave pseudopotential model
Authors: Mak D. K.
Published: April 2011

A method for calculating band masses, using an orthogonalized plane wave (OPW) formalism and taking into account the energy dependence of the pseudopotential form factors, is derived. This is applied to white tin; the results prove to be sensitive only to the energy dependence of the lowest form factor. Deformation potentials for various orbits have been calculated; they are found to be quite anisotropic over the Fermi surface.
Resonance and dispersion energies and the point-dipole model of atomic pair polarizability
Authors: Chandrasekharan V. , Tabisz G. C.
Published: April 2011

A simple model for atomic polarizability is used to calculate the long-range component of the atomic pair polarizability. The correct classical expressions for the excess pair polarizability and the anisotropy are obtained and shown to arise from the role of resonance forces in the interaction.
Image multiplexing with image retrieval using a slit source
Authors: Trivedi Sushma S. , Grover C. P.
Published: April 2011

An image modulated by a random spatial carrier is multiply recorded with a suitable displacement between successive exposures. If a slit source is used for illumination, the visibility of the fringes produced by such a recording depends upon the orientation of the slit with respect to the inter-exposure displacement. This fact has been made use of in the proposed method where the images to be multiplexed have their corresponding inter-exposure displacements lying in different directions. The images are retrieved using suitable binary filters whose transmission characteristics determine the cross-talk between the reconstructed images. A theoretical analysis of the method is presented.
Holographic imaging with a white light source: a novel technique
Authors: Grover C. P. , Tremblay R.
Published: April 2011

We illustrate a technique of white light holographic imaging where the subject wave undergoes small displacement during the recording of the hologram. If a suitable recording geometry is followed, this results in concentrating in a certain plane during reconstruction all the light diffracted by the hologram into a distribution resembling a horizontal slit. The hologram behaves like a rainbow hologram if it is set to disperse the incident white light along the direction of the subject displacement. Two methods based upon a continuous and discrete multiple displacement of the subject, respectively, along with the appropriate apodization techniques to reshape the modulation of the subject wave are described. The loss of resolution in the reconstructed image due to smearing caused by the subject displacement has been found to be far less important compared to that given by more dominating effect such as wavelength spread. The technique has been extended for application to the multicolor holography. The theory and some experimental results are presented.
An application of the inverse scattering method to the 3-wave interaction in nonlinear optics
Authors: Enns R. H. , Guenther D. B. , Rangnekar S. S.
Published: April 2011

The inverse scattering method is applied to the study of the stimulated Brillouin backscattering in an amplifier set-up of two light pulses whose envelopes are initially rectangular. The complete temporal and spatial evolution of the two pulses is obtained by analytically solving the Zakharov–Manakov problem under certain assumptions and approximations which may be readily satisfied experimentally.
First quantization of the spinning string
Authors: McKeon Gerry
Published: April 2011

The dual model of Neveu and Schwartz and of Raymond gives rise to the spinning string. Using a technique introduced by Rhorlich for the ordinary free string, we perform a first quantization of this spinning string. It is found that the procedure is covariant in any dimension with arbitrary Regge intercept.
Angular distribution of the 3H(p,γ)4He reaction at proton energies below 1 MeV
Authors: Bianco W. Del , Kajrys G.
Published: April 2011

The differential cross section of the 3H(p,γ)4He reaction has been measured at the proton energies Ep = 0.46, 0.50, 0.62, 0.77, and 0.93 MeV. A thin 3H–Ti target has been used and the γ-rays have been detected by a 12.7 cm diameter × 15.2 cm long NaI(Tl) crystal rotating over the angular range θL = 0 to 135°. The 3H(p,γ)4He reaction is found to proceed through E1, M1, and E2 transitions, E1 transitions being predominant. The ratio of the γ-ray flux at θL = 0 and 90° is energy dependent and decreases from 0.017 ± 0.003 at Ep = 0.46 MeV to 0.0078 ± 0.006 at Ep = 0.93 MeV.
The method of canonical transformations applied to the motion of a charge coupled to the electromagnetic field in the non-relativistic approximation
Authors: Battezzati M.
Published: April 2011

A method of canonical transformations extended to dissipative Hamiltonian systems in a previous article is here applied to study the behaviour of an extended charge coupled to the em field, as described by an approximate equation introduced by Caldirola, which is deducible from a Lagrangian function explicitly dependent on time. The generating function of a transformation which decouples the variables of the system is given, for an elastic applied force, and hence the constants of the motion are found by a general method. Some limit cases are examined.
Basis states for equivalent electrons. II. States for the Lie group Sp(4l + 2)
Authors: Ross William R.
Published: April 2011

The Slater basis states for N equivalent electrons form the basis for the irreducible representation (1N) of the Lie group U(4l + 2). States which are eigenfunctions of the total spin and total orbital angular momentum form the basis for irreducible representations of SO(3) × SU(2). In this paper the intermediate group Sp(4l + 2) is studied. The basis states for irreducible representations of Sp(4l + 2) are expressed in terms of the Slater basis states.
The phenomenological electromagnetic force density
Authors: Lahoz D. G. , Graham G. M.
Published: April 2011

The "current loop" model for a magnetic dipole is thoroughly examined in connection with the electromagnetic force density in material media. An updated and theoretically consistent expression for that force density is presented which differs from the Livens' and Page–Adams' proposals in minor details. The notation in our updated formula gives precise information about the volume elements within the material medium which are the seats where the different force density terms are localized. The corresponding tensor theory is also developed and, using the concept of localized Poynting vector, a new interpretation of the "Lorentz diffraction" phenomenology is suggested which would seem to explain the observed small deviations from the mean deflection.
Electron–electron scattering and the transport properties of liquid potassium
Authors: Cook J. G.
Published: April 2011

We report the results and interpretation of precision measurements of the thermal conductivity, electrical resistivity, and thermopower of potassium made from just below the melting temperature, 335.5 K, to 700 K. It is found that the Lorenz function is approximately 10% below the Sommerfeld value in the solid state, confirming previously reported data, that it increases approximately 4% upon melting, and that it then decreases slightly upon further heating to 700 K. All these features may be explained very well by the combined effect of electron–electron scattering and of scattering of electrons by ionic density fluctuations.
γ and π0 production in π− –emulsion interactions at 50 GeV/c
Authors: Sengupta P. K. , Goyal D. P. , Mozumder A. , Singh S.
Published: April 2011

The energy and momentum spectra of photons, based on 1017 electron pairs observed in an emulsion stack exposed to a 50 GeV/c π− beam, have been presented. We find, [Formula: see text], [Formula: see text], and [Formula: see text], where qT and qL are respectively the transverse and longitudinal momenta of the photon. Kopylov's relations are then used to obtain the corresponding π0 parameters. We obtain [Formula: see text] and [Formula: see text], where pT and pL represent respectively the transverse and longitudinal momenta of the π0.
The equations of immiscible viscous displacement in a porous medium
Authors: Spanos T. J. T.
Published: April 2011

A statistical theory for the construction of the equations of viscous displacement in a porous medium is considered. This yields a continuum theory for immiscible displacement which can be applied to either a homogeneous or inhomogeneous porous medium. The relative motions of the fluid are considered in terms of the motion of surfaces of constant saturation which are smoothed surfaces at the macroscopic scale considered. The boundary conditions and initial conditions at the injection boundary are considered as well as the boundary conditions and breakthrough conditions at the recovery boundary and the side boundary conditions. The inertial terms are included in the equations and shown to be of importance in describing these initial conditions and the breakthrough conditions.
Collision-induced absorption in ethylene in the microwave and far-infrared regions
Authors: Dagg I. R. , Read L. A. A. , Andrews B.
Published: April 2011

The collision-induced rotation–translation spectrum of gaseous ethylene has been measured at 295 K over a density range from 3.7 to 23.9 amagat in the 40–360 cm−1 region and at densities up to 50 amagat at 2.3 cm−1 and at 29.6 cm−1. The measurements were made using a Fourier transform spectrometer, an HCN laser, and a microwave cavity technique. Two spectral moments of the observed spectrum have been determined and used in a recently developed theory to provide values for the components of the quadrupole tensor of ethylene: Qxx = −3.54 × 10−26, Qyy = 1.77 × 10−26, Qzz = 1.77 × 10−26 esu. These values are compared with those obtained by other workers using different methods. The z direction is along the C–C axis, the y direction is in the plane of the molecule, and the x axis is perpendicular to the plane of the molecule.
Nuclear matter calculation with a super soft core potential including isobar degrees of freedom
Authors: Dey M. , Samanta B. C. , Dey J.
Published: April 2011

A complete nuclear matter calculation in lowest order Brueckner theory is done for a super soft core nucleon–nucleon potential due to de Tourreil, Rouben, and Sprung and the effect of including isobar degrees of freedom on binding energy, saturation, and half-shell G-matrices is considered in the frame work of the coupled channel formalism. The singlet and triplet S-state effective interaction is derived and its density and momentum dependence is studied. Comparison is made with the results obtained from the Reid soft core potential.
On the deterministic and stochastic stability of dissipative magnetohydrodynamic equilibria
Authors: Teichmann J.
Published: April 2011

The deterministic and stochastic stability of stationary equilibria of dissipative magnetohydrodynamics is discussed using the direct Liapunov method. The influence of random fluctuations on the stability is studied using three stochastic models.
Density of states for a structurally disordered Hubbard model
Authors: Liu K. L. , Bergersen B.
Published: April 2011

We study the density of states for a structurally random Hubbard model with a half-filled band. Calculations are carried out with the hopping integral t(R) obtained from a hydrogenic 1S wave function and with an on-site Coulomb repulsion [Formula: see text]. The equation of motion for the retarded single-particle Green's function is treated in the Hubbard III decoupling approximation. The configurational averaging for the Green's function is simplified using the approximation of Kikuchi. Coefficients in the locator–interactor expansion are calculated analytically up to seventh order in t. Several approximants for this formal series are investigated, including Padé approximant, continued fraction approximation, and quadratic Padé approximant. The last two approximants yield densities of state in satisfactory agreement with the result of Aoki and Kamimura in the high concentration region and our results are expected to represent an improvement for intermediate densities. However, for very low densities the Hubbard III scheme will underestimate the effect of spin correlations and our previous treatment in the U = ∞ limit would be more appropriate for the lower Hubbard band.
A method to accelerate convergence of Hartree–Fock calculations
Authors: Sprung D. W. L. , Vallières M.
Published: April 2011

An extrapolation procedure has been devised which secures convergence of static Hartree–Fock calculations in about a third fewer iterations than the standard methods.
The charge form factor of the model triton for two-particle interactions with continuum bound states
Authors: Pantis G. , Fiedeldey H. , Sprung D. W. L.
Published: April 2011

The charge form factor of the model triton clearly exhibits the collapse which occurs in the triton for purely nonlocal two-body interactions with continuum bound states and approaches an asymptotic shape with increasing binding energy. However, partly nonlocal interactions with continuum bound states, which previously have been shown not to produce such a collapse, also show no evidence whatsoever of the presence of the two-particle continuum bound state in the triton charge form factor. In the physically interesting case of partly nonlocal interactions the occurrence of a continuum bound state in the two-body interactions therefore can be completely harmless in the three-body system.
Some properties of metal-free amorphous phthalocyanine vacuum deposited films
Authors: Mindorff M. S. , Brodie D. E.
Published: April 2011

Amorphous metal free phthalocyanine films have been prepared by vacuum deposition of the powder onto quartz substrates cooled to liquid nitrogen temperatures. X-ray diffraction and differential thermal analysis have been used to study the crystallization (occurring between 325 and 410 K) to the α-phase and the subsequent irreversible phase change from the α- to the β-phase, near 480 K. Silver ohmic contacts with sandwich samples were used to study the I–V characteristics of amorphous phthalocyanine and the temperature dependence of the conductivity. Space charge limited currents with carrier densities of ~109 cm−3 and trap densities of ~1016 cm−3 are observed and the conductivity activation energy in the bulk is ~1.24 eV. Surface currents and surface traps were observed in planar samples and these dominate the bulk properties, for this geometry.
Deuteron induced fission in 233U
Authors: Mobed N. , Chatterjee M. L. , Beeley P. , Lee J. K. P.
Published: April 2011

The relative independent yields of Rb, Cs, and In from 233U(d,f) reaction were obtained at incident deuteron energies of 18, 31, and 44 MeV. From these mass distributions, the numbers of neutrons emitted per fission event were obtained and the charge division mechanism was investigated. Results indicated that within the energy region studied, the charge division process remained essentially the same as that for low energy events. The relatively larger widths of Cs distributions are explained in terms of dual stability zones around N = 82 and N = 86–88.
Ablative acceleration of thin foils driven by thermal power fluxes
Authors: Ahlborn Boye , Liese Wolfgang , Mayer Frederick J.
Published: April 2011

We have accelerated thin PVC foils by ablating the foil material in an electrothermal shock tube with power fluxes of typically 2 × 104 W/cm2 and 160 μs duration. The measured burn velocity, blow off velocity, and terminal velocity compare well with steady flow hydrodynamic considerations and a simple rocket model.
Angular distributions of the 12C(e,p)e′ reaction at Ee = 200 MeV
Authors: Lolos G. J. , Hontzeas S. , Sealock R. M.
Published: April 2011

Double differential cross sections at six angles ranging from 45° to 143° have been measured for the 12C(e,p)e′ reaction. The proton energy ranged from 15.6 to 17.2 MeV at an incident electron energy of 200 MeV. At the backward angles our results are in good agreement with data reported by Vysotskaya and Afanas'ev but for forward angles the results are lower.
Theory of phase transitions in solid methanes. XIV. The total neutron scattering cross section in phase II of solid CH4
Authors: Ozaki Yoshiaki , Kataoka Yosuke , Okada Kenkichi , Yamamoto Tsunenobu
Published: April 2011

The total neutron cross section in phase II of solid CH4 is calculated as a function of the incident energy E0 and the temperature in the ranges [Formula: see text] and [Formula: see text]. The sample is assumed to be a polycrystal and the neutron beam to be unpolarized. The total cross section consists of two parts: proton spin-independent and dependent parts. The latter is given by a sum of σ0 and σ′. Both the spin-independent part and σ0 come from the elastic scattering and can together be cast in the form [Formula: see text] for both Oh andD2d molecules, where [Formula: see text] is the mean squared proton spin angular momentum within a single molecule. The quantity σ′ depends on the details of the spin–rotational states. The calculated total cross section can again be expressed approximately as a linear function of [Formula: see text] as was empirically found by Lushington and Morrison (Can. J. Phys. 55, 1580 (1977)). A prediction is offered for a possible future experimental study.
Basis states for equivalent electrons. IV. States for the Lie group SO(2l + 1) × SU(2) using U(2l + 1) × SU(2) states
Authors: Ross William R.
Published: April 2011

In this paper we examine the irreducible representations of SO(2l + 1) × SU(2) that are present when we have equivalent electrons. Basis states for these irreducible representations are defined using the basis states for U(2l + 1) × SU(2). Using earlier results, where the U(2l + 1) × SU(2) states were defined using the U(4l + 2) states, we are able to express the SO(2l + 1) × SU(2) states in terms of the Slater basis states associated with the irreducible representation (1N) of U(4l + 2). The SO(2l + 1) × SU(2) states obtained in this paper using the intermediate group U(2l + 1) × SU(2) are compared with those obtained earlier using the intermediate group Sp(4l + 2).
Time-delay caused by scattering from an oscillating center of force
Authors: Hron M. , Razavy M.
Published: April 2011

Two different formulations of the problem of time-delay caused by scattering from an oscillating center of force are studied. In the first one, appropriate for local interactions, a semi-classical time-dependent solution of the Schrödinger equation is obtained by writing the wave function as a solution of two coupled equations one of which is the Hamilton–Jacobi equation. These equations are then solved using the narrow wave packet approximation. The classical motion of the center of this wave packet is found for two specific cases, a square well and a Morse potential. In the second formulation a time-independent many-channel solution of the Schrödinger equation is obtained for an exactly solvable quantum-mechanical problem with a potential consisting of a separable attractive part which oscillates and a fixed rigid wall. The results show that the time-delay is extremely sensitive to the values of the amplitude and the frequency of oscillations, and also to the energy of the incident particle.
The electronic emission spectrum of triatomic hydrogen. III. Infrared perpendicular bands near 3600 cm−1
Authors: Herzberg G. , Lew H. , Sloan J. J. , Watson J. K. G.
Published: April 2011

The experimental techniques for obtaining spectra of triatomic hydrogen are described with special reference to studies in the infrared. An electronic transition near 3600 cm−1 is observed in both H3 and D3. Its analysis shows that it is a 2A1′–2E′ transition and that the upper state is identical with the upper state 3s2A1′ of the 6025 Å band previously analysed (I. Dabrowski and G. Herzberg. Can. J. Phys. 58, 1238 (1980)) while the lower state is the upper state 3p2E′ of the 7100 Å band (G. Herzberg and J. K. G. Watson. Can. J. Phys. 58, 1250 (1980)). Improved constants are obtained for both these states from the infrared bands of H3 and D3. Perturbations in the upper state 3s2A1′ of D3 are clarified.
Neutron diffraction study of the structural changes in the antifluorite crystals Rb2PtI6, (NH4)2PtBr6, and (NH4)2PtI6
Authors: Sutton Mark , Armstrong Robin L. , Powell Brian M. , Buyers William J. L.
Published: April 2011

A neutron diffraction study of the structural phase transitions in Rb2PtI6, (NH4)2PtBr6, and (NH4)2PtI6 is presented. Cubic antifluorites studied to date exhibit transitions involving ferro- or antiferro-rotations of the halide octahedra with little or no tetragonal distortions. In this study we show that tetragonal distortions also occur in the antifluorites with or without accompanying rotations. Profile analysis reveals that below 65 K the Rb2PtI6 structure and below 50 K the (NH4)2PtBr6 structure become tetragonal with no evidence for rotation of the octahedra. Further, the 258 K transition in (NH4)2PtI6 is antiferro-rotative, with octahedra in successive (001) planes rotated in opposite senses, accompanied by a tetragonal distortion; the transition at 100 K involves a further ferro-rotation.
A phase space moment method for classical and quantal dynamics
Authors: Turner R. E. , Snider R. F.
Published: April 2011

A hierarchy of translational moment equations for the position and momentum observables is considered. The resulting set of equations is truncated in a manner that includes only first and second order moments. This closure procedure is consistent with the conservation of energy and, for spherically symmetric potentials, with the conservation of angular momentum. The method is valid for both classical and quantal mechanics with the only difference being that for quantal systems, the dispersions in momentum and position must satisfy Heisenberg's uncertainty principle. With finite dispersion in the position, the average position and momentum do not satisfy Hamilton's equations of motion since the average acceleration is modulated by the variance–covariance in the position. For classical systems, the second order moments may be taken to zero in which case Hamilton's equations are obtained. For quantal systems, a comparision is made with Heller's Gaussian wave packet approach. The moment method is illustrated by applying it to the reflection of a phase space packet from a one dimensional repulsive inverse square potential. Applications to the calculation of collision cross sections are envisaged.
Diffraction by a perfectly conducting elliptic cylinder in the presence of other scatterers
Authors: Hurd R. A. , Hayashi Y.
Published: April 2011

A solution is developed for scattering by a small, elliptic, perfectly conducting cylinder in the presence of an unspecified set of other scatterers, upon which an impedance boundary condition is allowed. The results are applied to two examples: an elliptic cylinder over an impedance plane, and an elliptic cylinder in a parallel plate waveguide.
Hydrodynamical description of the continuous Heisenberg chain
Authors: Turski Lukasz A.
Published: April 2011

The dynamical properties of a continuous Heisenberg chain (CHC) are analysed by means of the Lakshmanan variables. The least action principle for CHC is proposed and canonical formalism constructed following standard procedures.The instability of a finite amplitude spin wave excitation of the chain is analysed as an illustrative example.
Molecular dynamics study of solid nitrogen at high pressure
Authors: Klein Michael L. , Levesque D. , Weis J.-J.
Published: April 2011

A molecular dynamics study has been carried out of the structure and dynamics of solid nitrogen in its high pressure, room temperature, plastic crystal phase: cubic Pm3n. We employed a system of 512 molecules interacting via atom–atom potentials. As in the real solid our simulated crystal is composed of two types of molecules whose dynamical behaviour is quite distinct. We present calculations of the power spectra associated with translational and rotational motions as well as the phonon response embodied in the dynamical structure factor S(Q, ω).
82D3/2 ↔ 82D5/2 excitation transfer in rubidium induced in collisions with ground-state Rb atoms
Authors: Głódz M. , Atkinson J. B. , Krause L.
Published: April 2011

Cross sections for inelastic transfer between the 82D3/2 and 82D5/2 fine-structure states in rubidium, induced in resonant collisions with ground-state Rb atoms, have been determined using an experimental method involving two-photon excitation of atomic fluorescence. Rubidium vapor in a fluorescence cell was irradiated with pulses of 641 nm radiation from a N2 laser-pumped dye-laser tuned to excite one of the 82D states. The resulting fluorescence included the direct component originating from the optically excited state and a sensitized component arising from the other fine-structure state populated by collisions. Relative intensities of the fluorescent components, determined by photon-counting techniques, yielded the cross sections for excitation transfer: Q(2D3/2 → 2D5/2) = 8.1 × 10−13 cm2; Q(2D3/2 ← 2D5/2) = 5.5 × 1013 cm2; as well as [Formula: see text], the effective quenching cross section. The excitation transfer cross sections which are considered accurate to within ±20% are in the ratio predicted by the principle of detailed balancing.
Momentum distribution in liquid neon at 26.9 K
Authors: Sears V. F.
Published: April 2011

The momentum distribution function n(p) for liquid neon at T = 26.9 K on the saturated vapor curve is determined from an analysis of previously published neutron inelastic scattering measurements at large momentum transfer using a method developed originally for liquid helium. It is found that within the experimental accuracy n(p) is a Gaussian function of p with an effective temperature Teff = 32.1 ± 0.6 K that is 19% higher than the actual temperature. This value of Teff is in good agreement with the value 33.1 K calculated from an expansion in powers of [Formula: see text]. It is found that the [Formula: see text] correction gives a significant contribution (~ 4%) to Teff but that it does not produce any observable non-Gaussian distortion of n(p).
Specific heat of InBi below 30 K
Authors: Martin Douglas L.
Published: April 2011

There was difficulty in establishing good thermal contact with InBi, a very anisotropic material. This is not believed to have affected results from the 2.5–30 K adiabatic calorimeter. However, results from the 0.35–3 K isoperibol calorimeter are a few percent high in the overlap range owing to uncompensated heat loss during heating periods. Consequently there is some uncertainty in the determination of the electronic specific heat but little uncertainty in Debye temperatures above 1 K (because the lattice specific heat is so large). Despite the great anisotropy, mass-layering, and easy cleaving in one direction, the variation of Debye temperature with temperature is quite normal, there being no evidence of two-dimensional behavior (cf. graphite). The preferred analysis gives the electronic specific heat coefficient as 97.1 ± 0.8 μcal K−2 g-at.−1 (406 ± 3 μJ K−2 g-at.−1) and the low temperature limiting value of Debye temperature as 139.8 ± 0.4 K.
Mass splitting of beautiful baryons by weight diagram
Authors: Jallu M. Shafi , Ahmad Mubark
Published: April 2011

Electromagnetic weight diagrams for 3/2+ and 1/2+ baryons are drawn and sum rules are derived from the same. The conventional parallelogram law is modified so as to accommodate the hadrons with b quark contents in the four dimensional weight diagram.
Theory of resonant light scattering from two level atoms in the presence of collisions
Authors: Zaidi H. R.
Published: April 2011

A theory of resonant light scattering from two level atoms in a gas is developed for an arbitrarily strong pump field. The Doppler effect and two body foreign gas collisions are considered. Elastic, inelastic (upward and downward), and the velocity changing collisions are retained in the general formulation. The impact approximation is not made, and the expressions for all (field dependent) collision rates are generated internally. Particular attention is paid to the lower state interaction, and a more complete parameterization of the theory is achieved. The general theory is non-Markovian and the quantum regression theorem is not used; it reduces to existing theories in special cases. It is shown that the coherent scattering is not a general property of the system if the lower state interaction is present; the "coherent" component acquires a small, but nonzero, width in the strong field region. This width could provide information about some new collision parameters.
Parity-mixing above 30 MeV excitation energy in the 4He system
Authors: Bevelacqua J. J.
Published: April 2011

Parity-induced circular polarizations have been calculated for energy levels between 30 and 90 MeV excitation energy in the 4He system. The effective potential of Box, McKellar, Pick, and Lassey (BMPL) is utilized in the calculations. The results are based on detailed 4He wave functions which are calculated in a [Formula: see text] model space. The calculated circular polarizations (Pγ) are largest for Jπ = 1+ states at about 75 MeV excitation. These Pγ values are between 10−5 and 10−6 and are of the same order of magnitude as transitions measured in the 2H, 181Ta, and 203Tl systems. Circular polarizations based on the BMPL potential are within 15% of the Pγ values derived from the weak two-body potential of Desplanques and Missimer for the largest transitions considered in this study.
Influence of relativistic valence-core correlation on p-state fine structure in some univalent systems
Authors: Migdalek J. , Baylis W. E.
Published: April 2011

Single-configuration relativistic Hartree–Fock values of fine-structure separations are calculated for p-levels in systems with a single electron outside a closed-shell core, both with and without allowance for relaxation and polarization of the core. Effects of the polarization of the atomic core by the valence electron are included by the addition of a polarization potential to the one-electron Hamiltonian. The results obtained generally compare well with available experimental data and indicate a significant influence of core polarization on fine-structure splittings. Contributions of the relaxation of the core are considerable only for the heavier systems. The choice of the cut-off parameter r0 in the polarization potential, as well as of the shape of the cut-off function, and the success of the ab initio approach are discussed. It is suggested that for indium and thallium, in contrast to the case for rubidium, silver, and gold, the simplified picture of a core plus a single valence electron is no longer entirely satisfactory.
Density of states near the band edges in amorphous germanium
Authors: Tong B. Y. , Pant M. M. , Leung K. V.
Published: April 2011

We investigate the density of states near the edges of the band gap in tetrahedrally bonded amorphous semiconductors for a number of proposed structural models. This is made possible by using a cluster calculation method previously developed by us. Several techniques have been introduced to eliminate surface effects. The density of states near the band edge is shown to be sensitive to the characteristics of the model structure. Contrary to the usual concept that disorder introduces exponential tailing of the density of states into the energy gap, the presence of odd number rings (especially 5-member rings) makes the upper edge of the valence band drop faster with only a small tailing region. Large exponential tailing into the gap is induced by strain, i.e., stretching of bond lengths and distortion of bond angles.
Sharp line donor–acceptor pair luminescence in silicon
Authors: Ziemelis U. O. , Parsons R. R.
Published: April 2011

New sharp line structure observed in the near-band-edge (1030 to 1135 meV) photoluminescence of Si(P, In) and Si(B, In) at temperatures ranging from 1.6 to 20 K, has been identified as due to radiative recombination of electrons bound to phosphorus donors with holes bound to indium acceptors. This is the first study of sharp line, donor–acceptor pair luminescence in silicon. Straightforward analysis, assuming only Coulomb and van der Waals interactions between otherwise isolated donor and acceptor centres indicates that recombination involving P and In centres separated by distances ranging from 7.7 to 20 Å is responsible for the observed sharp line structure. This structure is superimposed on the high energy shoulder of the broad band luminescence associated with recombination involving distant (average separation: 55 Å) P–In pairs. Transient measurements indicate decay times ranging from 70 to 100 μs for the most prominent sharp lines and an overall decay pattern consistent with that expected for donor–acceptor pair recombination.