bluuebunny/crossref_metadata_2025 huggingface dataset:
Pion and kaon form factors in the statistical model
Authors: Banerjee S. N. , Das R. K.
Published: April 2011

The pion and kaon form factors have been studied in the context of the statistical model and the size of the meson is found to have a sensitive dependence upon the form of the form factor in the model.
On the transverse momentum of slow protons, deuterons, and pions in high energy interactions
Authors: Singh J. B.
Published: April 2011

A detailed analysis of transverse momentum spectra of slow protons, deuterons, and pions produced in proton emulsion interactions at 400 GeV and π−C interactions at 40 GeV has been made. Various statistical parameters have been used to test the different forms of the transverse momentum distributions. The nature of the pT distributions of all the particles is similar in π−–A and p–A interactions at both the energies.
The translational–rotational absorption spectrum of hydrogen
Authors: Bachet G. , Cohen E. R. , Dore P. , Birnbaum G.
Published: April 2011

The collision-induced translational–rotational spectrum of H2 has been accurately measured in the region from about 30 to 2000 cm−1 at 195 and 297 K. A very weak feature due to the hexadecapole-induced dipole, the U0(1) line, has been detected at 195 K in the region around 1622 cm−1. These spectra can be accurately represented by a simple, semi-empirical line shape. The effect of double transitions are considered and explicit expressions for these are given. Spectral integrals proportional to the zero and first moments are determined experimentally and compared with the theoretical moments computed on the basis of quadrupole induction for several potentials. The difference between the experimental and theoretical values, in the order of 20%, is attributed to anisotropic overlap induction, but the inferred magnitude of this component is strongly dependent on the assumed potential.
Rotational analysis and deperturbation of the C2Σ+–X2Σ+ band systems of BeH and BeD
Authors: Colin R. , Dreze C. , Steinhauer M.
Published: April 2011

A new C2Σ+–X2Σ+ transition of BeH and BeD is observed in a beryllium are in hydrogen or deuterium gas mixed with argon. The rotational analysis of the most intense of these strongly red degraded bands, which involve ν′ = 0–2 for BeH and ν′ = 0 for BeD, allows one to derive molecular constants for the new C2Σ+ state. The latter has a large internuclear equilibrium distance (re = 2.301 Å) and a shallow potential energy minimum [Formula: see text]. The principal molecular constants determined are:C2Σ+Tc = 30 953.94 cm−1[Formula: see text]Rotational perturbations between the C2Σ+ and A2Π states are observed in the C–X bands of BeH and BeD and in two new A–X bands of BeH (4–4 and 5–5) which have also been observed and analyzed. These perturbations are treated by a matrix approach and yield a value for the interaction matrix element [Formula: see text].The C–X bands analyzed involve the higher vibrational levels of the X2Σ+ state and allow, therefore, a substantial improvement of the ground state molecular constants to be made and a good Rydberg–Klein–Rees (RKR) potential energy curve to be calculated. The limiting curve of the predissociation confirms the previous value of the dissociation energy [Formula: see text] and indicates that a small maximum, less than 200 cm−1, could exist at [Formula: see text] in the ground state potential energy curve.Franck–Condon factors for the C2Σ+–X2Σ+ bands of BeH and BeD are also calculated.
Fusion cross sections for 14N + 11B at low energies
Authors: Dasmahapatra B. , Čujec B. , Lahlou F.
Published: April 2011

Fusion cross sections for the 14N + 11B system have been measured from Ec.m. = 2.85 to 8.53 MeV by the total γ-ray yield method. At energies just below the Coulomb barrier an enhancement similar to that present in the 12C + 13C system, but less prominent, has been observed. A comparison of various 14N-induced reactions shows that this enhancement is most prominent with an even–even target (12C, 16O), quite clear with an odd–even target (11B), and almost disappears with an odd–odd target (10B, 14N).
Intermolecular potentials from NMR data: H2–N2O and H2–CO2
Authors: Pandey Lakshman , Reddy C. P. K. , Sarkar K. Lalita
Published: April 2011

Proton spin-lattice relaxation times T1 were measured in mixtures of H2 with N2O as a function of density, composition, and temperature (200–400 K) in the region where [Formula: see text]. These data, along with the data obtained by Lalita and Bloom for H2–CO2, were interpreted, using Bloom–Oppenheim theory, to obtain the anisotropic intermoleeular potential parameters. Two models, (i) the Lennard–Jones (12–6) potential (LJP) and (ii) the modified Buckingham (exp-6) potential (MBP), were used to represent the isotropic part of the intermolecular potential. The relative anisotropy in the attractive r−6 term and the quadrupole moments of N2O and CO2 as obtained from MBP model are in better agreement with the values obtained from the polarizability data and the reported values, respectively, than those obtained from the LJP model.
Rotational analysis of the A1Π–X1Σ+ bands of 28Si34S: perturbation studies in the A1Π state
Authors: Krishnamurty G. , Gopal Sheila , Saraswathy P. , Lakshminarayana G.
Published: April 2011

The ultraviolet bands of the A1Π–X1Σ+ system of a 28Si34S molecule were excited in emission in an electrodeless discharge tube and photographed in the fourth order of a 10.6 m Ebert grating spectrograph. Rotational analysis of thirteen bands lying in the region 2600–3000 Å was carried out. Perturbations observed in the ν = 0–7 levels of A1Π were attributed to the perturbing states e3Σ−, d3Δ, C1Σ−, and D1Δ. Origins of the bands involving ν′ = 2, 6, and 7 were found to have shifted from their expected positions, presumably due to perturbations.
Synchronisation des modes lasers par modulation d'amplitude: analyse linéaire dans le domaine spectral
Authors: Piché M.
Published: April 2011

A theoretical study of homogeneous gain laser mode-locking by means of loss modulation is presented in this paper. A linear and causal mathematical formulation is used to describe the interaction between the laser field and the homogeneous medium. The frequency spectrum generated by the laser field is shown to satisfy a difference equation whose order is fixed by the Fourier expansion of the modulation function. Three types of solutions have been found to this equation: a family of uncoupled solutions called supermodes, a single solution, and a continuum of solutions. Unstable laser emission associated with a detuned modulation frequency is attributed to the onset of a continuum of solutions. A frequency filter with a small bandwidth suppresses such a continuum. As a result, the laser field quickly converges towards a stable profile over a broad band of modulation frequencies. [Translated by the journal]
Effects of energy dependence in the electronic density of states on some normal state properties
Authors: Mitrović B. , Carbotte J. P.
Published: April 2011

We study the effects of energy dependence in the electronic density of states (EDOS) on the electron quasiparticle properties in the normal state. The Migdal–Eliashberg equations generalized to include a nonconstant EDOS are derived in the isotropic approximation. By numerical solution of the electron self-energy equations in the normal state, we assess the effect of the interplay of the energy dependence in the EDOS, the electron–phonon interaction, and/or elastic impurity scattering on the electron quasiparticle properties. Self-consistency requirements are fully discussed.
Effective interactions for the configurations 3d44p +3d34s4p + 3d24s24p in the first spectrum of vanadium
Authors: Roth C.
Published: April 2011

Energy levels and Lande g-factors for the configurations 3d44p + 3d34s4p + 3d24s24p in the first spectra of vanadium were calculated and compared with experimental values. The calculations were clone in intermediate coupling taking into account explicitly the interactions between configurations, as well as complete effective interactions of the core, and effective interactions dp.Due to the insertion of the various effective interactions and a successful starting point based on a general treatment of the odd configurations in the first spectra of the iron group, there was excellent agreement between the experimental and calculated values.On fitting 233 levels using 28 free interaction parameters a mean error of only 133 cm−1 was obtained, i.e., about 0.4% average difference between the experimental and calculated levels. All the 438 predicted levels were calculated.The experimental and calculated g-factors corresponded very closely.
Some aspects of a continuous X-ray spectrum
Authors: Serr Kai
Published: April 2011

Planck's formula for blackbody radiation is modified to derive an expression for X-ray production from a thin anode. The continuous X-ray spectrum is explained in terms of electron backscatter losses and photon attenuation. The electron backscatter losses arc postulated to depend on the thickness of the anode and the energy of the incident electrons. Possible use of monochromatic X-rays for mammography is briefly discussed.
The infrared spectrum and molecular constants of CO2 in the 2 μm region
Authors: Arcas Ph. , Arie E. , Cuisenier M. , Maillard J. P.
Published: April 2011

The spectrum of CO2 has been recorded in the 2 μm region using high resolution Fourier transform spectroscopy. The effective constants have been determined with good accuracy for the (2001, 0401) and (211l, 0511) triads and the 0112–0000 transition. In addition, the vibrational energy of the (3001, 0601)1V level, previously given, has been corrected. The Coriolis resonance, strongly perturbing the (211e1, 051e1)m and (4000, 0800)n levels, has been studied.
A new spectrum of the PO2 radical
Authors: Verma R. D. , McCarthy Charles F.
Published: April 2011

A new spectrum in the region 3115–2680 Å has been obtained in absorption by a flash discharge technique, and is attributed to the PO2 radical. Vibronic and K structure analyses are performed which show conclusively that the new spectrum is analogous to the 2490 Å system of NO2, and thus represents the [Formula: see text] transition of the PO2 radical. The vibronic assignments are confirmed by an isotopic study of the spectrum using oxygen-18. The various frequencies obtained are: [Formula: see text], [Formula: see text], and [Formula: see text]. A predissociation is observed from which an upper limit to the energy of dissociation into P + O2 is set at 35 500 ± 100 cm−1.
A charged black hole in a uniform magnetic field
Authors: Krori K. D. , Chaudhury Sumita , Dowerah S.
Published: April 2011

We present here an investigation of the event horizon of a charged black hole embedded in a uniform magnetic field by studying the Gaussian curvature. It is shown that the Gauss–Bonnet theorem holds for this magnetized black hole and also for a magnetized Kerr black hole.
Méthode de fabrication et caractéristiques photographiques de photosystèmes de type Fabry-Pérot
Authors: Saint-Germain Daniel , Boivin Germain
Published: April 2011

The use of a Fabry-Pérot filter as a positive transmission photosystem is discussed first. Its construction is similar to an interference filter with multistacked mirrors. A lead–iodide and copper photosensitive element is made in such a way as to be combined with the multistacked mirrors. We then propose a method to fabricate the filter which is independent of the refractive indices of the materials. Finally, we present the sensitivity and contrast results of the photosystems.
Electron capture to positron branching ratios in the decay of 22Na and 44Sc
Authors: Baerg A. P.
Published: April 2011

The electron capture to positron branching ratios, e/β+, in the decay of 22Na and 44Sc have been re-measured by a new anticoincidence counting method. The results confirm the earlier values obtained by coincidence counting, but with a significantly reduced uncertainty. The new values are: 0.1079 ± 0.0003 for decay of 22Na to the 1.27 MeV level in 22Ne and 0.0499 ± 0.0005 for decay of 44Sc to the 1.16 MeV level in 44Ca.
The coexistence curve of GeH4 and correction-to-scaling
Authors: Balzarini D. , Mouritsen O. G. , Palffy-Muhoray P.
Published: April 2011

High-precision data for the coexistence curve of GeH4 covering the reduced temperature range 10−6 < t < 5 × 10−2 have been derived from measurements of the refractive index by focal plane interference methods. The data are analyzed in terms of correction-to-scaling confluent singularities, [Formula: see text], to yield the nonuniversal amplitudes. This is done by fitting the proposed theoretical expression to the data and by fixing the exponents to their renormalization group values. The data support the theoretical expression for [Formula: see text].
Masses of interstellar gas clouds
Authors: Bhatia V. B.
Published: April 2011

The equilibrium masses of the interstellar gas clouds have been calculated when the clouds are imbedded with magnetic fields. It is found that the masses of these clouds may be of the order of several thousand solar masses. These masses appear to be consistent with the generally accepted level of efficiency for the processes of star formation.
Target nucleus excitation dependence of correlation in the multiple production on nuclei at 400 GeV and the additive quark model
Authors: Ghosh Dipak , Roy Jaya , Banerjee Dipak , Sengupta Kaushik , Naha Sadhan , Basu Madhumita , Thakurta Tarit Guha
Published: April 2011

This paper presents a comparison of the data on the target nucleus excitation dependence of two-particle rapidity correlations among relativistic particles in hadron–nucleus interactions at 400 GeV/c with the additive quark model (AQM) for multiple production of particles off nuclei. The number of grey tracks (ng) has been taken as the parameter characterizing the degree of excitation. The dependence has been found to agree quantitatively with the predictions of the AQM.
BPHZ renormalization and surface terms in one loop diagrams
Authors: McKeon Gerry
Published: April 2011

The application of the Bogoliubov–Parasiuk–Hepp–Zimmermann renormalization scheme to one loop diagrams is discussed. A catalogue of useful integrals is presented. Anomalies induced by radiative corrections are examined from this point of view.
Absorption losses and thermal diffusivity of optical fibers investigated by photothermal methods: theory and experiments
Authors: Chardon Dominique , Huard Serge J.
Published: April 2011

Both the absorption coefficient and the thermal diffusivity of an optical fiber have been measured using photothermal methods: photoacoustics (P.A.) and photothermal deflection (P.D.). The amplitude of the photothermal signal is proportional to the heat density generated in the fiber core. This in turn is proportional to the light absorption coefficient β. Thus, these techniques allow one to separate the absorption and Rayleigh scattering losses. The results obtained by the two methods are in agreement. A threshold value of 10 dB km−1 mW has been determined experimentally. In both cases, the device is calibrated by replacing the fiber with a heated electric wire. Moreover, the heat must diffuse from the core to the gas so that when the light is modulated, a phase delay appears. A study of phase delay versus modulation frequency gives the thermal diffusivity of the fiber. This is required in order to improve fiber sensors.Theoretically, the cylindrical geometry of the sample permits simple calculations. The thermoelastic equations in solids and coupled thermodynamic ones in the gas have been solved without neglecting viscosity effects. Noting that silica is almost unexpansible, an algebraic expression of the signal has been obtained without any assumptions on the gas transformation processes. Finally, the P.A. and P.D. techniques are compared and some extensions are presented.
The first excited state of 9Be
Authors: Barker F. C.
Published: April 2011

An R-matrix fit to recent 9Be(γ,n)8Be cross-section measurements just above the neutron threshold gives parameters that are in reasonable agreement with those obtained from fits to data from other reactions.
Comparison between one- and two-dimensional models of a Raman pulse compressor
Authors: Marchand R. , Capjack C. E. , James C. R.
Published: April 2011

A simple method is presented for graphically comparing results from one-dimensional (plane wave) and two-dimensional calculations of a laser pulse compression by Raman backscattering. The effects of diffraction, generation of the second (or higher) Stokes pulse, and linear damping of the laser beams are assumed to be negligible.
Photovoltaic action spectra of metal–phthalocyanine Schottky barrier cells
Authors: Loutfy R. O. , Hsiao C. K. , Ho R.
Published: April 2011

We have measured the direct current (dc) action spectra of Al and In/phthalocyanine (α, β, and x-H2Pc and VOPc) photovoltaic cells in the wavelength range 400–900 nm. The data were analyzed in terms of both the local carrier generation and exciton diffusion models. According to the local carrier generation model, photoactive barrier widths w of 390, 475, 310, and 950 Å for In/α, β, x-H2Pc, and VOPc, respectively, were obtained. The depletion region width of In–phthalocyanine Schottky junctions were independently measured using a dc discharge capacitance technique. In all cases, the depletion region widths (capacitance) were consistently smaller than the photoactive collection region widths (action spectra). These results suggest that excitons produced within a diffusion length of the barrier can diffuse into the barrier zone and dissociate into collectable carriers. Using a combined local carrier generation and exciton diffusion model, a barrier width of the order of 200–300 Å and an exciton diffusion length of 300–500 Å was estimated for In/x-H2Pc cells.
About unidentified features in the Voyager far infrared spectra of Jupiter and Saturn
Authors: Gautier D. , Marten A. , Baluteau J. P. , Bachet G.
Published: April 2011

Two faint spectral features are visible in Jupiter's spectra recorded during the infrared interferometer experiment aboard the two spacecraft of the Voyager mission. These features are located at the frequencies of the S(0) and S(1) pressure induced rotation lines of the free H2 molecule, and are superimposed over the absorption spectrum induced by collisions between H2–H2 and H2–He molecules, which are the main components of the atmospheres of the giant planets. We demonstrate conclusively that these features are real and not measurement artifacts. The feature located at the S(0) frequency, which also exists in the Voyager spectra of Saturn, exhibits a complex shape, characterized by a lack of absorption in the continuum at 354.4 cm−1 and a local excess of absorption over the continuum at 350.5 cm−1. The feature corresponding to the S(1) frequency seems to be due mainly to an absorption dip in the continuum at 587.1 cm−1. Physical conditions prevailing at the atmospheric levels of formation of the features rule out the possibility that they can be attributed to H2 quadrupolar lines or to a dip in absorption resulting from intercollisional effects in the H2–He component of the pressure induced absorption. We speculate that they could be due to an intercollisional effect in the H2–H2 component, but the lack of laboratory measurements precludes any firm interpretation.Laboratory studies of the S lines in the collision induced spectrum of H2, made at high spectral resolution and low temperatures, are absolutely necessary in order to be able to complete the interpretation of the observed phenomena and to derive from them information on the atmospheric thermal structure or composition of Jupiter and Saturn.
Time evolution of a single-spin model coupled to a harmonic oscillator via the method of Mori
Authors: Pires A. S. T. , Gouvea M. E. de
Published: April 2011

We use Mori's memory function method for coupled operators to calculate the time-dependent behaviour of a single-spin model coupled to a harmonic oscillator. This model enables us to carry out the formal analysis of Mori exactly and gives us the physical insight required to treat more complex models, such as the Ising model in a transverse field coupled to phonons.
Electric dipole transitions from the 11.08 and 9.15 MeV levels in 17O
Authors: Rangacharyulu C. , Chatterjee M. B. , Pruneau C. , St-Pierre C.
Published: April 2011

In the 13C(α, γ)17O reaction, measurements of E1 transition strengths from the 11.078 and 9.148 MeV (Jπ = 1/2−) levels to the 0.871 MeV level give (10.4 ± 1.6) × 10−3and (2.4 ± 0.5) × 10−3 e2 fm2, respectively. The ratio of these transition strengths results in a polarization charge epol ≈ −0.6. The E1 transition strength from the 11.078 MeV level is in excellent agreement with the core-polarization calculation of Towner and Hardy. The asymmetry for the corresponding isovector E1 transitions in 17O and 17F is found to be [Formula: see text], comparable in magnitude with the asymmetry for the analogous [Formula: see text] decays of 17N and 17Ne.
Cumulative yields of stable and long-lived isotopes of tin in neutron-induced fission
Authors: Rosman K. J. R. , Laeter J. R. De , Boldeman J. W. , Thode H. G.
Published: April 2011

The relative cumulative fission yields of the six stable isotopes of tin (117Sn,118Sn, 119Sn, 120Sn, 122Sn, and 124Sn) and the long-lived isotope 126Sn have been measured in the thermal and epicadium neutron fission of 233U and 235U, and the epicadium neutron fission of 238U. Nanogram-sized fission product tin samples were extracted from irradiated uranium samples and analyzed in a solid source mass spectrometer. In each case a smooth curve can be drawn through the yield points of the seven isotopes of tin. There is, therefore, no evidence of "fine structure" in the 117 ≤ A ≤ 126 portion of the symmetric mass region.
Resonance Raman effect in TCNQ crystals
Authors: Carlone C. , Cyr C. , Jandl S. , Truong K. D. , Hota N. K. , Zauhar J.
Published: April 2011

Using the argon ion laser, the krypton ion laser, and the helium–neon laser, we have measured the Raman intensity of 13 phonons of TCNQ crystals, both at room temperature and at liquid nitrogen temperature. Besides the well-known resonance in the blue region (22 200 cm−1), we have also observed weaker resonances at 19 000 and 15 000 (± 2000 cm−1). The shape of the resonances is phonon dependent; the temperature behaviour is also phonon dependent. The results were reproducible on samples grown in three different laboratories. In only one sample did we also observe a fluorescence spectrum which is similar to the resonance Raman spectrum. From X-ray studies of the samples used, we deduce that there are slight structural differences among the samples, but the resonance Raman effect is independent of these differences. We surmise that the Raman intensity is sensitive to the presence of the [Formula: see text] radical anion in the crystals. The anion is formed either by impurities or by the photon.
Field solution of an annular slot array over a radial waveguide cavity
Authors: Shafai L. , Azarbar B.
Published: April 2011

The problem of a cavity-backed annular slot array is solved using appropriate Green's functions for the interior and exterior regions of the cavity. The excitation is assumed to be general in form and is defined in terms of radial waveguide modes. Both interior and exterior fields are obtained using a slot field distribution yet to be determined. The continuity of the tangential slot magnetic fields is then used to set up integral equations for the slot field distributions. These slot fields are represented by a finite number of pulse functions with unknown coefficients, which are then determined using a point matching technique. The method evaluates all slot fields simultaneously and as such includes all coupling effects between the various slots. The slot field distributions and their radiation fields are computed for different array sizes, and some representative results are presented.
Motional narrowing of the rotational Raman band of compressed CO, N2, and CO2
Authors: Tam R. C. H. , May A. D.
Published: April 2011

The depolarized rotational Raman, and depolarized Rayleigh spectra of compressed CO, N2, and CO2 were measured. The spectra, particularly that of CO2, show motional narrowing, collapsing to a single line at the laser frequency. The spectra are interpreted in terms of the J diffusion model and in terms of a simple two-line model spectrum. From the analyses, an empirical method is established for estimating the density at which motional narrowing will occur in rotational Raman bands. Two minor shortcomings in the J diffusion model are also identified.
Cross section of direct three-body breakup of 9Be for 1576-keV gamma rays
Authors: Fujishiro M. , Okamoto K. , Tsujimoto T.
Published: April 2011

Using 1576-keV γ-rays from 142Pr, the cross section of the direct three-body breakup of 9Be was measured and found to be (4.0 ± 1.8) × 10−1 μb. This result is in approximate agreement with Salyers' theoretical estimate based upon a cluster model of 9Be.
Magnetic susceptibility of the spin-glass with the itinerant-electron antiferromagnet as a host
Authors: Crişan M. , Gulácsi Zs. , Gulácsi M.
Published: April 2011

The magnetic susceptibility of the spin-glass state that may appear in an itinerant-electron antiferromagnet containing magnetic impurities has been calculated as a function of the temperature. The spin–spin interaction mediated by the condensed electrons has been calculated and a short-range interaction of the form (cos 2k0r/r2)e−r/ξ0 has been obtained. A percolation mechanism has been used in order to explain the occurrence of the spin-glass state.
Traitement unifié du modèle Heisenberg–Ising et du système de fermions correspondant
Authors: Spronken G. , Fourcade B.
Published: April 2011

It is shown that both the Heisenberg–Ising model and the corresponding fermion system yield the same recursion relation for the coefficients of the decomposition of any given eigenstate. The application of the Pauli exclusion principle to the latter model makes it possible to unify the treatment of the two systems. The problem is then reduced to constructing symmetric and antisymmetric Bethe wave function solutions of the recursion relation. Numerical results for the fermion system as a function of both the filling of the band and the interaction strength are presented.
NMR investigation of spin transfer to H in K2CuCl4∙2H2O
Authors: Han Tae Jong , Choh Sung Ho
Published: April 2011

Nuclear magnetic resonance of 1H in K2CuCl4∙2H2O has been measured with frequencies of 3 to 35 MHz at room temperature, 163, and 77 K. The fractional spin transfer from the copper ion to hydrogen due to the transferred hyperfine interaction is analyzed: 0.19 ± 0.03% at 300 K, 0.23 ± 0.02% at 163 K, and 0.27 ± 0.02% at 77 K, showing that the spin transfer is temperature dependent. This temperature dependence is closely associated with the unusually strong temperature dependent super-exchange interaction between Cu2+ ions in this crystal.
Interference effects in the spectrum of HD: I. The fundamental band of pure HD
Authors: Rich N. H. , McKellar A. R. W.
Published: April 2011

The absorption spectrum of the ν = 1 ← 0 band of HD has been investigated at a temperature of 77 K and for densities in the range of 15 to 140 amagat. The band consists of two components: a broad collision-induced quasi continuum arising from dipoles induced during molecular collisions; and a dipole-allowed part arising from the small permanent electric dipole moment of the free HD molecule. The interference effects which occur between these two components were studied for the dipole-allowed R1(0) and R1(1) transitions. These transitions exhibited increasingly large asymmetries and changes in intensity at high density, but their behaviours were quite different from each other. The shape of each transition could be well represented by a series of Fano line profiles, and the evolution of shape and intensity with density could be accounted for by the formulation of Herman, Tipping, and Poll. However, the precise interpretation of the phase shift parameters arising in the theory is not clear.
Microscopic optical potential analyses of carbon–carbon elastic scattering
Authors: Bidasaria H. B. , Townsend L. W.
Published: April 2011

Utilizing eikonal phase shifts determined from a microscopic double-folding optical potential, marked improvement in the agreement between theory and experiment, for elastic carbon–carbon scattering between 200 and 300 MeV, is obtained when only those values for the nucleon–nucleon slope parameter, appropriate for diffractive scattering, are used. The appropriateness of the perturbative eikonal expansion is discussed by comparison with recent results, obtained for the same potentials, using a more exact complex Wentzell–Kramers–Brillouin (WKB) formalism.
Discrete versus continuum relaxation modes of a hard sphere gas
Authors: Shizgal Bernard
Published: April 2011

The nature of the discrete spectrum of the linear Boltzmann collision operators for a simple gas and for a gas mixture is studied numerically with a discrete ordinate method. The discrete ordinate method is found to give a large number of discrete eigenvalues whereas the expansion method with Burnett functions yields only a few converged eigenvalues. The hard sphere cross section is used in the present paper although the methods employed are readily applicable to other cross sections. The approach of the eigenvalues to the continuum boundary is studied in detail and a comparison with a previous asymptotic Wentzell–Kramers–Brillouin (WKB) analysis yields excellent agreement.
Analogue–antianalogue transition for the 11.14-MeV level in 49V
Authors: Rangacharyulu C. , Pruneau C. , Chatterjee M. B. , St-Pierre C.
Published: April 2011

The g9/2 isobaric analogue resonance (IAR) is located at the excitation energy Ex = 11.139 MeV in 49V through the 48Ti(p, γ)49V reaction, (p, p1γ) angular distributions and the presence of the transition from the resonance to the 2.178-MeV (Jπ = 9/2+) level in 49V arc used to identify this resonance. The analogue–antianalogue M1 transition strength is found to be Γγ(M1) = 0.050 ± 0.009 eV or 0.2% of the single-particle estimate. This reduction in transition strength can be attributed partly to the fragmentation of the analogue and partly to the nonsingle-particle character of the antianalogue state.
Attribution of spins of proton capture resonances from gamma decay branching
Authors: Cameron J. A.
Published: April 2011

A method for estimating spins of highly excited nuclear states based on their gamma decay branching ratios is examined for sd and fp shell nuclei. Measures of similarity between emitting states have been made and a number of nuclei examined. Clear spin selectivity is observed in the spectrum similarities for resonant proton capture states in fp shell nuclei. In sd shell nuclei, the selectivity is weaker. The method of multidimensional scaling has been used to study the effect of spin on similarity using a large number of states of known spin in two test nuclei, 19F and 59Cu. Spin assignments are proposed for several resonances in 59Cu. Monte Carlo simulations were used to study factors influencing similarities and scaling configurations.
The spin-Hamiltonian parameter temperature dependence of the EPR spectra of Gd3+ impurity ions in Y(OH)3 and Eu(OH)3
Authors: Buckmaster H. A. , Malhotra V. M. , Boteler J. M.
Published: April 2011

The 9.23 GHz electron paramagnetic resonance (EPR) spectrum of ~1% Gd3+ impurity ions in Y(OH)3 and Eu(OH)3 monocrystals has been measured from 11 to 296 K. These spectra have been analyzed using a C3h symmetry, phenomenological spin-Hamiltonian. The temperature variation of the spin-Hamiltonian parameters was fitted to empirical root-mean-square (rms) best-fit expressions. It was found that the g values are linear functions of the temperature and that the nearest neighbour (nn) exchange interaction, Jnn = +0.23(5) cm−1 for (Gd3+−Eu3+) ion pairs, can be estimated from the single ion data. This is in satisfactory agreement with Jnn = +0.06(9) cm−1 obtained from ion pair data. The temperature variation of the zero field splitting (ZFS) parameters B20 and B40was found to fit cubic expressions over the temperature measurement interval and the magnitude of B20 increased as the temperature increased, corroborating the earlier conclusion that the host lattice effect in the Ln(OH)3 series cannot be explained using a point charge model for the crystalline electric field.
A study of argon metastable generation in a hollow cathode arc
Authors: Fortin Marc , Meubus Paul
Published: April 2011

A study is made of the intense spectroscopic continuum obtained between 120 and 180 nm for an argon–helium mixture (15% He) deexcitation, the emission originating from a hollow cathode arc discharge operated at 2900 K and a calculated pressure of 20 kPa. The deexcitation of the excimers toward the repulsive fundamental level gives way to an ultraviolet (UV) continuum, which is a characteristic of the potential energy curve for these molecules and whose position in the wavelength scale depends on the temperature of the hollow cathode. This continuum is identified as the second Tanaka continuum.Absolute radiation measurements have been made with a gold coated photocathode in order to determine the excited rare gas molecules [Formula: see text] concentration, which is in the order of 7 × 1013 cm−3.Such concentrations are high and seem to be related to the generation means used (hollow cathode).The spectroscopic results obtained with the indicated specific argon–helium mixture imply a major contribution of a precursor of the type (He–Ar)+ for the [Formula: see text] metastable formation.
Gamma-ray cross sections and effective atomic numbers in some alloys in the energy range 32 to 662 keV
Authors: Babu K. Suresh , Lingam S. Chandra , Reddy D. V. Krishna
Published: April 2011

Total attenuation cross sections in four alloys, telphy, dilver P, anhyster DS, and anhyster M, at 32.1, 52, 72.1, 84.3, 145.4, 279.2, and 661.6-keV photon energies are measured in a good geometry setup using two NaI(Tl) scintillation detectors for low and medium energy photons. Experimental total attenuation cross sections are compared with the theoretical values of Storm and Israel and found to be within experimental error. Using the subtraction method, photoelectric and scattering cross sections are obtained at appropriate photon energies and compared with theoretical values. The effective atomic numbers for photoelectric and total gamma-ray interactions are derived and their variation with energy is discussed.
Analytic expressions for fluorescence spectra and optical collision rates of collisionally perturbed atoms in a strong driving field
Authors: Schuller F. , Nienhuis G.
Published: April 2011

We have studied the problem of a collisionally perturbed two-level atom in an intense driving field by developing a method which allows us to calculate the field-dependent collision operator in terms of the low intensity field-independent line-broadening function arising in the usual unified theory of pressure broadening. Our relations are exact to all orders in the field in the limiting case of weak collisions, but they are exact also in the complementary case of strong collisions and weak fields. We apply our results to derive explicit expressions for the rate of optical collisions, the fluorescence spectrum in the case of well-separated components, and the absorption during an adiabatic square pulse.
Total cross sections for electron–lithium scattering
Authors: Tayal S. S. , Tripathi A. N.
Published: April 2011

We have calculated electron–lithium total scattering cross sections using the simplified second Born and corrected static approximations. The results of the present calculations have been compared with the estimated values of Walters and available experimental data.
Charge transfer in H+–He+(1s) collisions
Authors: Datta Shyamal , Mandal C. R. , Mukherjee S. C.
Published: April 2011

A new straightforward technique for the calculation of cross sections for electron capture by structureless ions into arbitrary n, l, and m states from the ground state of hydrogenic targets has been presented in the framework of the continuum–intermediate state approximation. We reduce the scattering amplitude to a closed analytical form. We apply this method for the nonsymmetric process H+ + He+(1s) → H(1s, 2s, 2p, 3s, 3p, 3d) + He2+ in the laboratory energy range 50–10 000 keV. Our calculated results are compared with experimental data and existing theoretical calculations.
Etude à basse température dans l'infrarouge proche du dimère (NO)2
Authors: Menoux V. , Doucen R. Le , Haeusler C. , Deroche J. C.
Published: April 2011

The spectrum of the dimer (NO)2 in the gas phase has been studied in the near infrared at temperatures between 118 and 138 K. More specifically, the measure of absorption intensity of the ν4 and ν1 + ν4 bands has yielded the heat of formation of the dimer, −2.25 kcal/mol at 128 K, and revealed the influence of the low vibrational modes on this measure. The observation of the ν4 – ν6, difference band has yielded the wave number value of the ν6, fundamental band, forbidden in the infrared. The rotational constants of the vibrationally excited state were found to be larger than the ground state rotational constants, this result being very unusual.
Emission spectra of group IV monohalide ions: , 3Π1–X1Σ+ emissions of SiBr+
Authors: Tsuji M. , Shinohara K. , Nishitani S. , Mizuguchi T. , Nishimura Y.
Published: April 2011

Emission spectra of SiBr4 in the rare gas flowing afterglows have been measured to detect and identify SiBr+ emissions. Two systems of SiBr+ emissions were detected in the He, Ne, and Ar afterglows in the region from 335 to 380 nm. By analogy with the emission spectrum of SiCl+, they were ascribed to the [Formula: see text]–X1Σ+ and a3Π1–X1Σ+ subsystems of SiBr+. The vibrational analysis of the latter system gave the following molecular constants for the a3Π1 state: T0 = 29 140 ± 5 cm−1 and ΔG(1/2) = 392.0 ± 3.7 cm−1. The SiBr+ emissions disappeared when ionic species were removed from the afterglows, indicating that the emitting SiBr+ states were produced through thermal-energy reactions of rare gas ions with SiBr4. In the He and Ne afterglows, the [Formula: see text] ions were produced in higher vibrational levels than in the Ar afterglow. The relative vibrational populations in the He and Ne afterglows were nearly exponential with an effective vibrational temperature of 460 ± 30 K.
The spin susceptibility of an amorphous Hubbard model
Authors: Liu K. L.
Published: April 2011

We study the temperature-dependent spin susceptibility of a structurally disordered Hubbard model with a quasi-exponential transfer integral based on a hydrogenic 1 s wavefunction. The electronic hopping is treated perturbatively up to fourth order. The susceptibility is calculated for various atomic concentrations and electronic densities and for different strengths of on-site Coulomb repulsion. Contact is made with the measured susceptibility of lightly doped semiconductors. The possibility for ferromagnetism in the model is examined and conclusions analogous to Nagaoka's theorem and Kanamori's theory are obtained. Finally, using a generalized Kirkwood superposition approximation for the many-body distribution functions, we have investigated the influence of short-range atomic correlation on the magnetic properties.
Dynamics of the lower thermosphere consistent with satellite observations of 5577 Å airglow: I. Method of analysis
Authors: Murphree J. S. , Elphinstone R. D. , Cogger L. L.
Published: April 2011

Numerical solutions of the continuity equation for atomic oxygen in the altitude range 80 to 120 km have been obtained for the purpose of investigating the various possible causes of latitudinal and seasonal variation in the atomic oxygen layer. The calculations take into account both photochemical and dynamical processes. Included in the dynamical processes are transport due to molecular diffusion, eddy turbulence, and time-independent macroscopic winds. The model allows the influence of these transport processes on the atomic oxygen altitude profile to be quantitatively evaluated. It is designed to provide a method to characterize the atomic oxygen profile by physical parameters for subsequent use in the interpretation of long-term temporal and latitudinal variation of 5577 Å airglow observations.
Spin symmetry energy and spin dependence of the single particle potential in nuclear matter
Authors: Dabrowski Janusz
Published: April 2011

In the presence of tensor nuclear forces, the single particle energy in spin and spin–isospin polarized nuclear matter is diagonal in nucleon spin states with the spin quantization axis tilting away from the direction in which nuclear matter is polarized. This tilting of nucleon spins is taken into account in determining the shape of Fermi surfaces in spin and spin–isospin polarized nuclear matter, and in relating the spin and spin–isospin dependent components of the single particle potential, and the spin and spin–isospin symmetry energies of nuclear matter to the Landau parameters of the quasi-particle interaction. Numerical results are obtained partly with empirical values of the Landau parameters, and partly with values calculated with the Sprung effective two-body interaction in nuclear matter.
High resolution study of the absorption spectrum of the first positive system of N2
Authors: Verma R. D.
Published: April 2011

The first positive system of N2, B3Πg – A3Σu+, has been obtained in absorption by the flash discharge technique. From a high resolution spectrum, a rotational analysis of the 12–8, 13–9, 14–10, 15–11, 13–8, and 14–9 bands has been carried out. Information on the B3Πg, ν = 13, 14, and 15, and A3Σu+, ν = 9, 10, and 11 levels is reported for the first time.
Polarization dependence of resonant multiphoton ionization in atomic mercury
Authors: Dalby F. W. , Pryce M. H. L. , Sanders J. H.
Published: April 2011

The polarization dependences of a number of resonant multiphoton ionizations in atomic Hg have been studied experimentally and theoretically. Good agreement between theory and experiment is found from which quantitive information about relative ionization cross sections from excited states has been deduced.
Unitary approximations to transition probabilities: Generalized impact parameter theory and the time dependent projection operator method
Authors: Turner Ralph Eric
Published: April 2011

A general unitary approximation scheme is presented for transition probabilities based upon the application of the time dependent version of the Zwanzig–Feshbach projection operator method to the generalized impact parameter approximation. The overall approximation scheme is based upon the time dependent picture of the binary collision process. To begin with, the translational and internal motions are decoupled with the translational motion being treated in one of three ways, namely, as a straight line trajectory, as a single curved reference classical trajectory, or as a collection of such trajectories, each of which is associated with a pair of internal states. The internal dynamics is then parameterized by the set of given trajectories which are functions of the impact parameter. This motion is then formally solved using the Zwanzig–Feshbach projection operator method. A set of unitary approximations to these solutions are then presented, based upon a time disordered approximation. These latter approximations are applicable to each of the three treatments of the translational motion. As well, the basis used to describe the internal degrees of freedom may be either atomic or molecular (diabatic or adiabatic). Thus this combined approximation scheme provides a systematic theory for testing various effects associated with either the treatment of the translational motion or the internal motion.
Absolute absorption cross sections at high resolution in the A2Πi – X2Πi band system of ClO
Authors: Barton S. A. , Coxon J. A. , Roychowdhury U. K.
Published: April 2011

Chlorine monoxide (ClO) has been produced at temperatures near 315 K in a fast-flow system at total pressures (of argon diluent) in the range 1.0–2.0 mm Hg. The transmittance of ultraviolet radiation has been determined with a spectral resolution of 0.0054 nm for all 35ClO ν′–0 A2Π3/2 – X2Π3/2 sub-bands in the range 3 ≤ ν′ ≤ 12 (305.9–274.9 nm). The ClO column density obtained with 8 or 12 traversals of the radiation along an 80 cm cell was in the range 1.0–2.0 × 1017 cm−2.The experimental transmittance profiles for each sub-band have been reproduced closely by synthetic spectrum calculations. The parameters required as input to the programs were optimized by nonlinear least-squares techniques. The fitted (Lorentzian) linewidths are on average more than double those previously reported from visual estimates of linewidths on photographic plates. The fitted band strengths lead to a well-defined electronic transition moment variation for the A – X system of ClO, which is in excellent agreement with an earlier determination by Mandelman and Nicholls from spectra at lower resolution (0.22 nm) with unresolved rotational structure.
Les intensités dans les bandes ν5, ν7 et ν8 + ν11 de l'éthane 12C2H6
Authors: Dang-Nhu M. , Pine A. S. , Lafferty W. J.
Published: April 2011

The intensity parameters of the ν5, ν7, and ν8 + ν11(A2u) bands of 12C2H4 have been determined from the experimental line strengths recorded in the 3 μm region with an infrared difference-frequency laser spectrometer.
Rechargeable nonaqueous lithium/Mo6S8 battery
Authors: Mulhern P. J. , Haering R. R.
Published: April 2011

Electrochemical cells based on the intercalation of lithium into Mo6S8 were examined by derivative constant current chronopotentiometry, in situ X-ray diffraction, and long-term cycling. About three-quarters of the capacity of such cells oeeurs between 2.0 and 2.1 V with most of the remainder near 2.45 V. Li/Mo6S8 cells have a long cycle life, good discharge rate capability, and an energy density of at least 260 W∙h/kg (1 W∙h = 3.6 kJ) of active material. Such cells can be made by starting with cathodes made from ternary Chevrel phase compounds. AyMo6S8 (A = Cu, Fe, Ni), and electrochemically converting these materials to form LixMo6S8.
Étude expérimentale de propriétés piézo-optiques du CCl4 liquide
Authors: St-Arnaud J. M. , Bose T. K.
Published: April 2011

We have developed a measuring system based on the Michelson interferometer for the determination of piezo-optical effects in liquids. The resolution of our system is about 5 parts in 107. We applied our system to the measurement of the variation of the refractive index of CCl4 at 25 °C up to 1.96 × 103 bar. We observe a slight deviation of the Lorentz–Lorenz equation at high pressures.
Infrared spectrum of TCNQ crystals
Authors: Carlone C. , Lemieux M. A. , Deslandes J. , Jandl S. , Truong K. D. , Hota N. K. , Zauhar J.
Published: April 2011

The reflectivity spectrum from the (001) surface of TCNQ crystals was recorded between 4200 and 50 cm−1. Only two peaks were observed. The ωLO, ωTO, γLO, and γTO for each mode are 226, 224, 11.4, 6.9, and 477, 476, 5.2, and 3.4 cm−1 respectively; εx is 2.49 for each mode. These data show weak dipole moments in the compound. The absorption spectrum in the same region was also recorded. Three hundred and twenty-seven transitions were observed, most of which were overtones and combinations. The temperature dependence (10–300 K) of the phonons was obtained. Its behaviour confirms mode mixing in the crystal. The reflectivity spectrum and the soft modes occur approximately in the region where one expects a gap between the internal and external modes. We associate charge transfer with mode mixing.
Étude par relaxation nucléaire du proton et du deutérium des mouvements moléculaires dans l'iodopropyne liquide
Authors: Tourki R. , Fried F. , Seurin M. J. , Gaymard F. , Sixou P.
Published: April 2011

Proton and deuterium relaxation times of liquid iodopropyne are measured at various temperatures. The separation of proton relaxation into its main parts, intra- and intermolecular dipolar mechanisms and spin-rotation, is achieved by a dilution study in deuterated iodopropyne. Molecular motions are analyzed by using the rotational diffusion model extended to the case of symmetric top molecules.