bluuebunny/crossref_metadata_2025 huggingface dataset:
The new formula for gravitational-radiation energy loss and the axially symmetric two-body problem
Authors: Cooperstock F. I. , Lim P. H.
Published: April 2011

We present the new formula for gravitational-radiation energy loss that replaces the familiar quadrupole formula. The new formula helps to clarify why the quadrupole formula works when it does. The origin of the correction tensor is discussed and then applied to the axially symmetric two-body problem. With the conventional equation of state, ε = ε(P), the correction tensor vanishes and the radiation is that of the bulk-motion quadrupole formula. This is to be compared with our earlier result with an unconventional equation of state giving more radiation and with that of critics claiming dominant radiation via internal motions with the quadrupole formula. An order-of-magnitude calculation is performed for a binary system, where it is found that there is the potential for contributions from nonlinear terms to be as significant as those from the linear terms after(Gm/α)−5/6 orbits. This occurs after ~102 years for the binary pulsar PSR1913 + 16.
Charged spinor solitons
Authors: Mathieu P. , Morris T. F.
Published: April 2011

A nonlinear Dirac equation for which all finite-energy stationary solutions are nontopological solitons with compact support is coupled to the electromagnetic field. In a many-body situation, it is shown that the equilibrium is reached when all the solitons have the same value of the charge. This implies the de Broglie frequency relation and a relation for the fine-structure constant. In specific domains and to a very good approximation, the model reduces to the linear Dirac equation for a particle whose mass parameter is the static energy of the soliton.
Matter in superstrong magnetic fields
Authors: Skjervold J. E. , Østgaard E.
Published: April 2011

The behaviour of condensed matter in superstrong magnetic fields of the order of 1012–1015 G is investigated, i.e., binding energies of atoms in condensed matter are calculated by a variational method. The cohesive energy, i.e., the difference between the binding energies of free atoms and of atoms in condensed matter, is also calculated, and results are obtained for hydrogen, helium, carbon, oxygen, silicon, and iron atoms.For a magnetic field of 1012 G, we obtain binding energies for atoms in condensed matter of 0.2 keV for hydrogen, 0.7 keV for helium, 4.5 keV for carbon, 7.4 keV for oxygen, 20.0 keV for silicon, and 59.0 keV for iron. For a magnetic field of 1014 G, we get corresponding binding energies of 1.2 keV for hydrogen, 3.9 keV for helium, 27.0 keV for carbon, 44.9 keV for oxygen, 121.5 keV for silicon, and 366 keV for iron. For a magnetic field of 1012 G, we obtain cohesive energies of 0.04 keV for hydrogen, 0.10 keV for helium, 0.36 keV for carbon, 0.51 keV for oxygen, 1.4 keV for silicon, and 2.8 keV for iron. For a magnetic field of 1014 G, we get corresponding cohesive energies of 0.16 keV for hydrogen, 0.40 keV for helium, 1.9 keV for carbon, 3.0 keV for oxygen, 7.3 keV for silicon, and 19.4 keV for iron.
Indices de réfraction des mélanges MgF2 – PbCl2 et Na3AlF6 – PbCl2
Authors: Saint-Germain Daniel , Boivin Germain
Published: April 2011

An experimental study of the refractive indexes of MgF2–PbCl2 and Na3AlF6–PbCl2 mixtures is presented. These mixtures are produced by vacuum co-evaporation, and the evaporation rates are controlled by a variable-size evaporation source. The refractive index and concentration behavior are described for each mixture by adjusting the form factor of the ellipsoid, generalized Maxwell–Garnett law. We discuss the meaning of this law and the various parameters involved in the mixtures' behavior.
Some interesting aspects of total disintegration of heavy emulsion nuclei at high energies
Authors: Khushnood H. , Shakeel A. , Irfan M. , Ahmad A. , Naqvi A. H. , Shafi M.
Published: April 2011

Analysis of the events having Nh ≥ 28 produced in 50 GeV pion (π)−–Em and 400 GeV proton (p)–Em interactions and the results obtained at different incident energies reveal that the probability of total disintegration of the target nuclei and the value of [Formula: see text] strongly depend on the mass of the incident particle as well as the target nuclei. This probability is observed to be independent of the energy of the projectile in p–Em reactions but not in π−–Em collisions. The mean normalized multiplicity, R4, calculated in terms of the created charged particles, is independent of the identity and energy of the impinging hadron beyond ~20 Gev. Furthermore, the values of [Formula: see text] and [Formula: see text] are observed to depend weakly on the energy of the projectile. The maximum number of charged particles constituting a cluster is observed to be four at both incident energies; the characteristics of clusters are observed to be independent of the nature and energy of the impinging hadron.
High-resolution studies of the near-ultraviolet bands of oxygen: I: the system
Authors: Ramsay D. A.
Published: April 2011

Ten new bands of the [Formula: see text] system of oxygen have been found using longer absorption paths than in the earlier work of Herzberg (1953). Rotational assignments and molecular constants are given for all bands from ν′ = 1–16. The principal constants for the [Formula: see text] state are as follows:[Formula: see text]
Two-photon lepto-production: a partial-wave analysis
Authors: Roberts Winston
Published: April 2011

A partial-wave analysis is carried out on the process γγ → 1+1− and the results compared with a similar analysis for 1+1− → γγ. Possible applications for hadronization processes are briefly discussed.
The dielectric behaviour of dipolar mixtures I: chlorobenzene–nitrobenzene mixtures
Authors: Hanna F. F. , Abdel-Nour K. N. , Ghoneim A. M.
Published: April 2011

The dielectric absorption of dilute solutions of nitrobenzene, chlorobenzene, and their mixtures in cyclohexane and Decalin® have been measured in the microwave region at three temperatures between 20 and 40 °C. The relaxation times and thermodynamic parameters are determined. A single relaxation time is found for the mixtures, and the results are discussed.
Study of the 127I(γ,n)126I reaction
Authors: Tsai J-S. , Prestwich W. V. , Kennett T. J.
Published: April 2011

The photoneutron spectrum arising from the 127I(γ,n)126I reaction, when induced by monochromatic 9.72-MeV neutron-capture γ rays, has been investigated with a 3He neutron spectrometer. From an evaluation of the energies of the emitted neutrons, several excited states of 126I have been determined. The states deduced are in general agreement with earlier findings, albeit some of the peaks observed in the present experiment may correspond to unresolved neutron groups populating several closely spaced levels. In addition to the observation of a new level at 146 keV, the reaction Q value is found to be 9145 ± 3 keV.
Spin- equations with tachyons and complex energies in small external fields
Authors: Labonté Gilles
Published: April 2011

One normally identifies the prediction of tachyons with a higher spin problem. We show that the same phenomenon also happens with certain spin-[Formula: see text] equations, in exactly the same circumstances. Furthermore, we prove that these equations also have the defect of possessing solutions with complex energies, even with the smallest external fields. The consequences of these results are analyzed.
Sources of the emission features between 2000 and 8000 Å in the thermosphere
Authors: Sharp William E.
Published: April 2011

The sources and sinks of the emission features from the atoms and molecules of the atmosphere are reviewed. The thermo-spheric emissions between 2000 and 8000 Å are reviewed specifically. There is much work that remains to be done with the visible emissions.
Interference effects in the spectrum of HD: V. the pure rotational and fundamental bands of liquid HD
Authors: Clouter M. J. , McKellar A. R. W.
Published: April 2011

The infrared absorption spectrum of HD has been studied in the liquid phase at temperatures between 17 and 35 K. Results were obtained for the region of the pure rotational R0(0) transition in the far infrared (80–95 cm−1), and for the fundamental band in the mid infrared (3600–4000 cm−1), using a temperature-controlled moderate-pressure cell with a 1.5-cm path length and a Fourier-transform infrared spectrometer. The R0(0) line was found to have a symmetric shape, a rather narrow width (from 1.3 to 1.8 cm−1), and an intensity that is moderately enhanced by interference effects. The R1(0) transition was found to have a more complicated asymmetrie shape due to interference effects, and at low temperatures was found to consist of (at least) two components, which strongly resemble those observed in solid HD.
On the quenching of Gamow–Teller strength
Authors: Rapaport J.
Published: April 2011

The (p, n) reaction at intermediate energies has been used to measure differential cross sections in light nuclei to final states characterized with a ΔJπ = 1+ transfer (Gamow–Teller (GT) states). Experimental ft values for allowed beta-decay transitions in these nuclei are used to normalize the strength of the GT transitions in units of B(GT). This experimental GT strength is compared with predicted shell–model strength. For p-shell nuclei, the calculated excitation energies of the GT strength using Cohen and Kurath wave functions are in general agreement with the empirical GT distribution. Up to an excitation energy of about 20 MeV, the total experimental and calculated GT strengths are used to obtain the quenching factor, QF = Σ B(GT)exp/Σ B(GT)theor. It is found that QF decreases as the shell gets filled-up. The lowest value seems to occur for single-hole nuclei. This decrease may be explained by configuration mixing not specifically included in the calculations.
Gamow–Teller strength functions from scattering experiments
Authors: Häusser O.
Published: April 2011

We present here recent [Formula: see text] results from TRIUMF that are relevant to the determination of spin-flip isovector strength functions in nuclei. Distortion factors needed for the extraction of nuclear-structure information have been deduced from cross sections and analyzing powers in elastic scattering for several energies and targets. Nonrelativistic optical potentials obtained by folding effective nucleon (N)–nucleus interactions with nuclear densities are found to overpredict both elastic and reaction cross sections, whereas Dirac calculations that include Pauli blocking are in good agreement with the data. Spin observables (Snn and Ay) for the quasi-elastic region in 54Fe[Formula: see text] at 290 MeV provide some evidence for the reduction of the effective proton mass predicted in relativistic mean-field theories as a consequence of the attractive scalar field in the nuclear medium. The energy dependence of the effective N–nucleus interaction at small momentum transfers has been investigated using isoscalar and isovector 1+ states in 28Si as probe states. We find that the cross sections for the isovector transitions are in good agreement with predictions for the dominant Vστ part of the Franey–Love interaction. Gamow–Teller (GT) strength functions have been obtained in 24Mg and 54Fe from measurements of both cross sections and spin–flip probabilities Snn. The spin-flip cross sections σSnn are particularly useful in heavier nuclei to discriminate against a continuous background of ΔS = 0 excitations. In the (s, d) shell where full shell-model wave functions are available, the GT quenching factors [Formula: see text] are in good agreement with those from recent (p, n) and (n, p) experiments. We show that a state-by-state comparison of (p, p′) and (e, e′) results has the potential of identifying pionic current contributions in (e, e′). The GT quenching factors in 54Fe are smaller than in the (s, d) shell probably because of severely truncated shell-model wave functions, particularly those of the nuclear ground state.
The use of rapid solidification processes in search of new hard magnetic materials
Authors: Hadjipanayis G. C.
Published: April 2011

Rapid solidification can be used to prepare amorphous and other metastable phases and special microstructures that cannot be obtained otherwise. The melt-spinning technique has been used for R15Fe77B8 and SmCo5−xNix alloys in a search for new hard magnetic materials. In R15Fe77B8, the as-quenched samples had an amorphous structure that on heating, crystallized into a fine-grained microstructure with R2Fe14B as the major phase. The grain-size range was 200–4000 Å, leading to coercivities that were much higher than those in sintered magnets. In SmCo5−xNix, melt-spinning produced both a fine-grained microstructure and a higher degree of atomic disorder, leading to substantially higher coercivity than was obtained in as-cast alloys.
The A2Π–X2Σ+ system of MgCl
Authors: Singh M. , Ghodgaonkar G. S. , Saksena M. D.
Published: April 2011

The A2Π–X2Σ+ system of MgCl has been photographed at high resolution and analyzed for the rotational structure. Analysis of the low-frequency sub-bands of the 0–0, 0–1, and 0–2 bands showed that there is a nonzero Λ doubling in the common vibrational level ν′ = 0, thereby indicating that the A2Π state is regular and not inverted as presumed by earlier workers. Spin-doubling has been seen in the ν = 1 and 2 levels of the X2Σ+ state. Rotational analysis of the high-frequency sub-band has also been done for the 0–0 band.
Core-polarization-corrected multiconfiguration Dirac–Fock oscillator strengths and excitation energies for the 5s2 1S0 – 5s5p 3P1, 1P1 transitions in Sr I and Y II spectra
Authors: Migdalek J. , Baylis W. E.
Published: April 2011

Energies and oscillator strengths for the spin-allowed 5s2 1S0 – 5s5p 1P1 and spin-forbidden 5s2 1S0 – 5s5p 3P1 transitions in neutral strontium and singly ionized yttrium are determined in relativistic multiconfiguration Dirac–Fock computations where modest relativistic configuration mixing to represent intravalence correlation is combined with a polarization model to account for valence–core electron correlation. It is demonstrated, by comparison of the results corrected for electron correlation with those obtained from relativistic intermediate coupling Dirac–Fock calculations, that both intravalence and core–valence correlation are important for achieving good agreement with experiment. However, for neutral strontium it is the intravalence correlation that seems to be more important whereas for the isoelectronic singly ionized yttrium the core-valence correlation, as represented by the core-polarization model, dominates. A delicate balance resulting from the partial collapse of the 4d orbital in Y+ may be a reason for the greater sensitivity to core polarization in this system.
Raman studies on N2 – rare-gas mixed crystals
Authors: Löwen H. W. , Jodl H. J. , Loewenschuss A. , Däufer H.
Published: April 2011

Raman spectra of solid nitrogen and of mixed N2–rare gases (RG-Ar, Kr, Xe) are investigated over a concentration range as wide as allowed by the pertinent experimental conditions. Both the v(N2) and the lattice-mode region are studied. The effects of changes in RG impurity concentrations and temperature variations are described. Results are discussed in terms of "matrix effects," like frequency shifts, on one hand and "solid-state" effects, like resonance splitting of the vibrational transition, vibron–phonon coupling, and one- and two-phonon transitions, on the other.
Anomalies in a two-dimensional supergravity model
Authors: Ho-Kim Q. , Montminy M.
Published: April 2011

It is shown that the first-order quantum violations of conservation of supercurrent in a complex two-dimensional model of supergravity coupled to matter can be cancelled by finite, local counterterms.
Behaviour of a sonic wave in dissociating gases
Authors: Rai Arisudan , Gaur M.
Published: April 2011

The present communication is devoted to the study of weak solutions of the system of hyperbolic partial differential equations in dissociating gas flows. As an application of the singular surface theory, the law of propagation and the growth equation of a sonic wave are obtained, and the breakdown of a sonic wave is also discussed. It is found that weak disturbances in dissociating gases propagate with the effective velocity of sound relative to the gas flow. The effects of dissociation and the wave geometry on the global behaviour of the wave amplitude are discussed. It is concluded that dissociation has a stabilizing effect on the sonic wave in the sense that either it disallows or delays shock formation. The two cases of diverging and converging waves are discussed separately.
Crystallization of Zn-rich and P-rich amorphous Zn3P2 thin films
Authors: Arsenault C. J. , Brodie D. E.
Published: April 2011

Zn-rich and P-rich amorphous Zn3P2 thin films were prepared by co-evaporation of the excess element during the normal Zn3P2 deposition. X-ray diffraction techniques were used to investigate the structural properties and the crystallization process. Agglomeration of the excess element within the as-made amorphous Zn3P2 thin film accounted for the structural properties observed after annealing the sample. Electrical measurements showed that excess Zn reduces the conductivity activation energy and increases the conductivity, while excess P up to 15 at.% does not alter the electrical properties significantly.
Resonance recombination of spin-polarized atomic hydrogen at low temperatures
Authors: Reynolds M. W. , Hardy W. N.
Published: April 2011

In sufficiently large magnetic fields, the weakly bound levels of H2 acquire finite lifetimes owing to hyperfine predissociation and become manifest as scattering resonances in spin-polarized atomic hydrogen (H↓). In this work we investigate in detail the contribution to the reaction kinetics in H↓ due to the resonance, denoted [Formula: see text], arising from the predissociation of the (v,J) = (14,4) level of H2. To characterize the formation and disintegration of [Formula: see text], we calculate the predissociation as a function of both the applied magnetic field and the dissociation energy, D, of the level. Recombination occurs when [Formula: see text] is stabilized in collisions that cause transitions to lower molecular levels. For low H↓, densities, collisions with atoms of the saturated 4He vapour dominate; we calculate the cross section in the distorted wave Born approximation and also use a coupled-channels approach. At higher densities, stabilization occurs in collisions with H↓ as well; the effect of proton exchange between the atom and the molecule is derived. Previous experiments, analyzed neglecting proton exchange, are reanalyzed including this; the dissociation energy D is not as well determined by the data as was previously thought. Prospects for future experiments are discussed.
Lattice dynamics and intrinsic phonon broadening in the alloy Cu0.92Ge0.08
Authors: Hallman E. D. , Svensson E. C.
Published: April 2011

Using inelastic scattering of slow neutrons, we have determined the phonon frequencies and intrinsic line widths for the dilute face-centred cubic alloy Cu0.92Ge0.08 (Cu(Ge)) at 296 K. A limited number of measurements have also been made at 96 and 500 K. Spectrometer resolution calculations, using actual instrument and specimen parameters, have been performed and intrinsic phonon widths have been obtained by deconvolution from observed widths. The phonons in Cu(Ge) are well defined and similar to those for copper. Real contributions of the force-constant disorder in the alloy to intrinsic phonon widths are seen. To our knowledge, this is the first time that such effects have been conclusively observed for such dilute alloys. Constituent-atom mass differences are small for this alloy, and no mass disorder effects have been observed. Born–von Kármán model force-constant fits to the frequency data at 296 K are presented and compared with a model for pure copper. The frequency distribution and other thermal data, including the temperature dependence of the specific heat, the Debye–Waller factor, and the Debye temperature, are also given. The Cu(Ge) force constants are compared with those for 14 other iron-group transition elements and alloys. Systematic trends in the force constants as a function of 3d + 4s electron concentration are apparent.
Action for the Maxwell–Einstein multiplet from nine-dimensional superspace
Authors: Xiaoan Zhou
Published: April 2011

The starting point is the Einstein–Hilbert action in nine-dimensional superspace. A special Dirac spinor with only half the degrees of freedom is defined in five-dimensional spacetime. The massless Kaluza–Klein ansatz is used in the dimensional reduction. After this reduction to four dimensions, the action contains a (minimal) supergravity multiplet, a Maxwell multiplet, and a scalar, which corresponds to the oscillation around the extra dimension. The locally supersymmetric (off-mass shell) Maxwell-Einstein action is obtained as a special case of the vanishing oscillation around the extra dimension.
High-resolution studies of the Herzberg band system (C1Σ+ – A1Π]) in the 13C18O molecule
Authors: Kępa R.
Published: April 2011

Seven bands ((0–0) – (0–6)) belonging to the Herzberg system of 13C18O have been recorded in emission using conventional photographic spectroscopy. For the first time, lines of this system have been recorded at high resolution and identified. After the rotational analysis of bands, the rotational constants of the C1Σ+ (ν = 0) and A1Π (ν = 0–6) states, as well as the vibrational constants of the A1Π state, have been determined. A combined analysis of the bands of the Herzberg and Ångström systems have made it possible to determine the constants of the B1Σ+ state more precisely. Numerous rotational perturbations observed in the A1Π state in this isotopic molecule have been analyzed.
Probabilistic-topological theory of systems with discrete interactions: II. Calculation of the hypergraph probabilistic representation; the difference a posteriori algorithm
Authors: Klonowski Wlodzimierz
Published: April 2011

The scheme of calculations, which subsequently will be called the difference a posteriori algorithm (or just DAPOST), is formulated in a general and rigorous manner to make its application to different systems with discrete interactions (SDI) possible. The DAPOST enables one to calculate important probabilistic characteristics of SDI while having only general information about its composition and interactions between system elements. The DAPOST is easily adaptable to very different physicochemical and biophysical systems, especially to the problems of element aggregation and binding. When applied together with a hypergraph representation of the SDI under consideration the DAPOST allows construction of equivalent probabilistic representations of the hypergraph modelling the SDI, in this way often considerably simplifying calculations of the structure–property relationships of the SDI.
The 12C(3He, γ1+2)15O reaction in the giant dipole resonance region
Authors: Kim J. C. , Kajrys G. , Bianco W. Del
Published: April 2011

The 90° differential cross section of the 12C(3He, γ1+2)15O reaction has been measured at 3He particle energies from 5.3 to 16.7 MeV in steps varying from 100 to 300 keV. The γ-rays were detected by a 23 cm long × 23 cm diameter NaI(Tl) crystal spectrometer enclosed in an anticoincidence shield. The yield curve shows a resonant behaviour at the energies Ex = 17.56 ± 0.06, 19.02 ± 0.12, and 23.80 ± 0.10 MeV.
Complete disintegration of heavy nuclei induced by 340 GeV negative pions
Authors: Ahmad Tauseef , Tariq M. , Irfan M. , Zafar M. , Ahsan M. Z. , Shah M.
Published: April 2011

The total disintegration of AgBr nuclei caused by 340 GeV negative pions is investigated. The probability of this phenomena depends on the energy of the pion projectile. The angular distributions of grey and black tracks are investigated. Results for the rapidity gap correlation in these catastrophic destructions are also presented.
A test of quantum 1/f noise using α decay
Authors: Jones B. K. , Berry M. G. , Hughes G.
Published: April 2011

Experimental verification of the theory of quantum 1/f noise is not easy. Measurements have been previously reported on the statistics of nuclear α decay that claimed to observe the effect. This experiment has repeated the study of the α decay and concludes that there is no good evidence for the effect.
A new property of superstring tree amplitude
Authors: Chung Won-Sang , Kim Jae-Kwan
Published: April 2011

The N-point correlator of the superstring is decomposed into N – 3 four-point correlators in calculating the N-point tree amplitude.
Lateral distribution and energy spectra of high-energy muons in cosmic-ray air showers
Authors: Basak D. K. , Sarkar S. K. , Mukherjee N. , Sanyal S. , Ghosh B. , Chaudhuri N.
Published: April 2011

The energy spectra and the lateral distribution of muons in cosmic-ray air showers, in the size range 104–106 particles as measured by two magnetic spectrographs each of full detection efficiency for muons in the energy range 2.5–500 GeV, are presented along with the derived muon size vs. shower size results. Comparisons with similar recent experimental data and calculations are given to infer the cosmic-ray primary composition.
Interfacial wave theory of dendrite growth: global mode solution and quantum condition
Authors: Xu Jian-Jun
Published: April 2011

This paper is concerned with the global mode solutions of dendritic crystal growth. In this paper, we investigate the signal feed-back process at the leading edge of the dendrite tip and derive the global instability mechanism of the system on the basis of the previous results (Phys. Rev. A, 40, 1599 (1989); 40, 1609 (1989)). A global wave diagram of the system is explored, which we call WEASR (Wave emission at the turning point and signal reflections between the turning point and the leading edge of the tip). This WEASR mechanism determines a discrete set of unstable global modes for the system. The asymptotic solutions for these modes and the quantum condition for the corresponding eigenvalues are obtained. The discovery of the WEASR mechanism is quite a significant step leading to the understanding of instability phenomena in dendrite growth.
Path-integral approach to anomalies at finite temperature
Authors: Treml T. F.
Published: April 2011

The non-Abelian chiral anomaly for a fermion interacting with an external vector field in any even dimension and the conformal anomaly, in the limit of flat space–time, for a self-interacting scalar field are shown to be independent of temperature using a simple path-integral approach that employs dimensional regularization. The chiral anomaly is used as an example to show that the methods used to study the dimensionally regularized anomaly at finite temperature are readily transferable to the case of ζ-function regularization. The conformal anomaly in (super) string theory at finite temperature is briefly discussed in the light of known results. Some subtleties concerning the use of infrared cutoffs in a dimensionally regularized approach to the computation of the one-loop effective action at finite temperature are considered in an appendix.
Single-crystal Mössbauer study of phlogopite mica
Authors: Hargraves P. , Rancourt D. G. , Lalonde E.
Published: April 2011

In this first single-crystal Mössbauer study of mica we have measured the room-temperature spectra for different orientations (with respect to the -γ-ray flux) of a well-characterized monocrystalline wafer of natural phlogopite. We apply a new method (D. G. Rancourt, Nucl. Instrum. Methods Phys. Res. B44, 199 (1989). of performing thickness corrections, which yields the intrinsic absorber cross section. The simplest physical model that is consistent with all the spectra is described as follows. The Fe2+ spectral contribution is due to correlated distributions of hyperfine electric-field gradient (efg) magnitudes and directions that can be understood in terms of two families of octahedral sites: a cis-like family having a narrower distribution of larger efg magnitudes and directions in the ab-plane and probably along the b axis, and a trans-like defect family having a broader distribution of smaller efg magnitudes and more out-of-plane efg directions. The Fe3+ spectral component is also due to broad and correlated distributions of efg magnitudes and directions. Its efg components have signs opposite to those of Fe2+, with e2qQ > 0 and mostly out-of-plane directions. Contrary to many claims in the literature, we show that: (i) thickness effects are not negligible, (ii) meaningful cis/trans spectral-area ratios cannot be obtained by attempting to resolve the relevant overlapping spectral components, (iii) information concerning the hidden Fe3+ spectral lines (i.e., the low-energy components of Fe3+ quadrupole doublets) is impossible to obtain, and (iv) resolving the Fe3+ into cis and trans components is, at best, questionable.
Roton and vibron density of states in solid parahydrogen
Authors: Bose S. K. , Poll J. D.
Published: April 2011

We present the results for the density of states of J = 2 rotons and ν = 1 vibrons in solid (hcp) parahydrogen as well as the joint roton–vibron density of states for noninteracting rotons and vibrons. The width and the shape of the joint roton–vibron density of states agree with those of the Raman and IR spectra in the 4490–4520 cm−1 spectral region lending support to the idea that the latter are due to the Q1(0) + S0(0) double transitions in the fundamental band of solid parahydrogen. However, there are differences between the features of the experimental (Raman and IR) spectra and the joint density of states that indicate that the matrix element effects and perhaps also the effects of interaction between the rotons and the vibrons are important in determining the exact features in these spectra.
Electronic properties of superlattices
Authors: Aitelhabti D. , Vasilopoulos P. , Currie J. F.
Published: April 2011

Using the transfer-matrix method, we evaluate the exact normalized wave function analytically, the band structure, and the current density associated with an electron in a superlattice, with different or equal effective masses between wells and barriers. Also, we evaluate numerically the dispersion relation, the bandwidth, and the current density (in the tight-binding limit) for both equal and different effective masses between wells and barriers.
The effects of substrate temperature on reactively evaporated a-Si:H
Authors: Zhang S. , Audas R. G. , Brodie D. E.
Published: April 2011

The bonding configurations and the concentrations of hydrogen are important parameters that affect the electrical and optical properties as well as the Staebler–Wronsky effect. Infrared transmission measurements are used as the main technique to investigate the effect of substrate temperature Ts on the hydrogen content and bonding configurations in reactively evaporated a-Si:H. There is no measurable SiH peak in films made at low Ts. When Ts is increased to 450 K, the SiH peak is discernable, and the maximum SiH concentration is obtained for Ts = 540 K. SiH2 and(or) (SiH2)n concentrations are large at low Ts but decrease as Ts is increased. When samples made at low Ts are stored in air at room temperature, they take up oxygen and the SiH2 and(or) (SiH2)n concentration decreases with time after preparation. This phenomenon is not observed for samples made with Ts ≥ 540 K. The dark conductivity, optical band gap, and electrical activation energy are altered by varying the H concentration. When some samples [Formula: see text] are illuminated with AM1 radiation, a conductivity change of more than three orders of magnitude has been observed.
Higher dimensional Gödel-type cosmologies
Authors: Krori K. D. , Goswami D.
Published: April 2011

We present in this paper a study of higher dimensional Gödel-type cosmologies in the following cases: (i) with a perfect fluid and (ii) with cosmic strings. In the latter case we show that the string tension density may be a constant or a variable if the number of dimensions is four but it is only a constant if the number of dimensions is larger than four.
Study of plasma disruptions and their suppression by a fast-ramping current in the STOR-1M tokamak
Authors: Sarkissian A. , Hirose A. , Zhang W. , Mark K. , Skarsgard H. M.
Published: April 2011

Minor and major disruptions, preceded by the growth of m = 2 and m = 3 modes, are observed during normal discharges on the STOR-1M tokamak, when the plasma safety factor on the plasma surface, q(a), becomes lower than 3 or with strong gas-puffing. It has been demonstrated that stable low-q discharges, with q(a) as low as 1.6 can be obtained and maintained for durations longer than the growth time for resistive tearing modes, if the plasma current is ramped up rapidly through a disruptive q region defined by 1.85 < q(a) < 2.1. The boundaries of the disruptive q region do not change when the maximum current ramp-up rate is varied between 0.5–2 kA μs−1.
Quantum description of microwave passive circuits
Authors: Marinescu Nicolae , Nistor Rudolf
Published: April 2011

The paper gives a formal analogy between the distribution of the electromagnetic field in a wave guide and microwave cavities and the quantum-mechanical probabilities distribution. We show that the wave guide of the cutoff frequency ωc acts on an electromagnetic wave as a quantum potential barrier [Formula: see text]. We also establish a nonhabitual time-independent Schrödinger equation that replaces Maxwell's equations in describing guided wave propagation.
Scalar finite-element evaluation of cut-off wavelength in glass wave guides and comparison with experiment
Authors: Lamouche Guy , Najafi S. Iraj
Published: April 2011

The scalar finite-element method is used to analyze ion-exchanged glass channel waveguides. Cut-off wavelengths for fundamental and first-order modes are calculated and the single-mode region is determined. The results are compared with the experimentally measured values.
Positron annihilation in simple condensed gases
Authors: Stewart A. T. , Briscoe C. V. , Steinbacher J. J.
Published: April 2011

The angular-correlation technique of positron annihilation has been used to detect and measure the localized bubble state of positronium (Ps) in liquid Ne, Ar, Kr, H2, and N2 and in liquid and solid He at various pressures and temperatures. No bubble state was seen in liquid O2 or in solid Ne and Ar. The dynamics of bubble formation is not yet understood. In the cases where theoretical calculations, and adequate data, exist, viz. He, Ar, and H2, there is reasonable agreement for the momentum of the photons from the annihilation of positrons with the outer electrons of these atoms. The Ps annihilations from the self-trapped bubble state are reasonably well described in terms of a simple finite potential-well model.
Magnetism of a graphite bi-intercalation compound with two types of ferromagnetic layers: double hysteretic transition in CrCl3–NiCl2–C
Authors: Rancourt D. G. , Flandrois S. , Biensan P. , Lamarche G.
Published: April 2011

An atomic-scale multilayer with two types of ferromagnetic layers is achieved by graphite intercalation. It is a bi-intercalation compound with stacking sequence CrCl3NiCl2NiCl2/… where/represents a graphite layer. The two types of chloride layers are much as they occur in the pristine chlorides and have the same lattice parameters and intralayer intertransition–metal ferromagnetic exchange interactions. The transition temperatures for singly intercalated CrCl3 and NiCl2 graphite compounds are, respectively, 11.3, and 20.2 K. The bi-intercalation compound shows a "double transition" with Tc1 and Tc2 being equal to the relevant intercalate-specific temperatures. It is proposed that, as the temperature is lowered, the NiCl2 layers order first at Tc2 into a 3-D antiferromagnetic stacking of ferromagnetic planes, followed by onset of intra-CrCl3-layer ferromagnetic order at Tc1. Below Tc1 the two types of ferromagnetic planes probably assume a 3-D antiferromagnetic stacking that involve both types of layers, requiring that the NiCl2 stacking be different than at Tc1 < T < Tc2. The main interlayer interactions are believed to be dipole–dipole forces and these are seen to give large low-field temperature hysteresis effects. This is in contrast to many layered materials with antiferromagnetic in-plane interactions in which: (i) dipole–dipole forces do not play a significant role, (ii) 3-D order is not intercalate specific but occurs at temperatures that are much lower than the in-plane interaction strengths and that are highly dependent on the interlayer interaction strengths, and (iii) hysteresis effects are not observed.
The octopole and hexadecapole moments of N2O from collision-induced absorption measurements
Authors: Dagg I. R. , Anderson A. , Gmach T. F. , Joslin C. G. , Smith W.
Published: April 2011

The absorption spectrum of gaseous N2O was measured in the spectral region from approximately 15–120 cm−1 at 11 different densities from 3.3 to 64.5 amagat. (An amagat is defined as the density of a gas at N.T.P.) The data were obtained with a Michelson Fourier transform IR spectrometer and a far IR laser using a stainless steel absorption cell 9.26 cm in length. From the density dependence of the absorption, the collision-induced spectrum above approximately 60 cm−1 was clearly separated from the relatively strong allowed transitions peaking at the lower frequency near 22 cm−1. From theoretical expressions for the line shape, derived using information theory, and a reliable value of the quadrupole moment (obtained from the birefringent measurements), we estimate the octopole moment to be 7.6 × 10−34 esu and the hexadecapole moment to be 16.9 × 10−42 esu. Alternatively, if the hexadecapolar contribution is considered to be negligible, then we estimate the octopole moment to be 9 × 10−34 esu. These results are consistent with measurements of the total integrated absorption of the IR band assuming a theoretical expression for the contribution due to the allowed dipole transitions.
Noncompact orthosympletic supersymmetry: an example from N = 1, d = 1 supersymmetric quantum mechanics
Authors: Schmitt H. A. , Mufti A.
Published: April 2011

The supersymmetric quantum mechanical harmonic oscillator, a particular example of an N = 1, d = 1 supersymmetric quantum mechanical model, is used to construct a Hamiltonian exhibiting a noncompact orthosymplectic supersymmetry. This Hamiltonian is the strong-coupling limit of the Jaynes–Cummings model.
Rheological effects of non-Newtonian fluids on natural convection in a porous medium
Authors: Pascal H.
Published: April 2011

The question of the rheological effects of non-Newtonian fluids on the natural convection mechanism in a porous medium is addressed. These effects are illustrated for a power-law fluid with a yield stress, in which the yield stress is temperature dependent. The case of a constant-temperature boundary along a heated vertical plate embedded in a porous medium is investigated. For this case the approximate self-similar solutions in closed form of steady and transient states are presented and discussed. The rheological effects on the convection pattern are shown.
Characteristics of clusters produced in 340 GeV π− – nucleus interactions
Authors: Naser Mustafa Abdusalam , Irfan M.
Published: April 2011

An attempt is made to examine the characteristics of clusters in 340 GeV π− – A interactions. Results reveal that the maximum number of relativistic charged particles constituting a cluster is four and the cluster size is independent of the target mass. Finally, the cluster size is observed to be insensitive to the identity and energy of the colliding hadrons for energies ~ 50 GeV and beyond.
Conversion-electron and gamma–gamma directional correlation measurements in 134Ba
Authors: Chand Bakhshish , Goswamy Jatinder , Mehta Devinder , Singh Nirmal , Trehan P. N.
Published: April 2011

Conversion electrons from the decay of 134Cs have been investigated using a mini-orange electron spectrometer. The electron intensities for the K-conversion of 242.7 keV and L, (M + N … ) conversion of 563.2, 795.9, 801.9, 1038.6, 1167.9, and 1365.2 keV transitions in 134Ba are being reported for the first time. The conversion-electron data have been further used to determine the conversion coefficients for various transitions in, 34Ba. Also, the gamma–gamma directional correlation measurements for seven cascades in 134Ba have been carried out using a HPGe–HPGe detector coincidence setup. The multipole admixtures for the 475.3, 563.2, 569.3, 795.9, 801.9, 1038.6, and 1365.2 keV transitions have been deduced from these measurements. A multipole admixture of M1 + 37% E2 has been obtained for the 1038.6 keV transition in 134Ba. The reduced transition probability ratios for the transitions de-exciting second 2+ and 3+ energy levels in 134Ba have been calculated and compared with the values predicted by the triaxial rotor model for γ = 28.5°. This indicates the softness of the, 134Ba nucleus toward γ deformation.
The 4d95p transitions in the tenth spectrum of cesium, Cs X
Authors: Joshi Y. N. , Arcimowicz B.
Published: April 2011

The spectrum of cesium was photographed in the 850–400 Å (1 Å = 10−10 m) wavelength region. Nineteen lines were interpreted as transitions between the 4d95s and 4d95p configurations. All levels of the 4d10, 4d95s, and 4d95p configurations were established. Least-squares-fitted parametric calculations and Hartree–Fock ab initio calculations support the analyses.
Local kinetic analysis of low-frequency electrostatic modes in tokamaks
Authors: Hirose A.
Published: April 2011

Analysis, based on a local kinetic dispersion relation in the tokamak magnetic geometry incorporating the ion transit frequency and trapped electrons, indicates that modes with positive frequencies are predominant. Unstable "drift"-type modes can have frequencies well above the diamagnetic frequency. They have been identified as the destabilized ion acoustic mode suffering little ion Landau damping even when [Formula: see text].
Reactive evaporation of BaF2 in water vapour for in situ growth of YBa2Cu3Ox thin films
Authors: Gao Yuan , Cline R. W. , Tiedje T.
Published: April 2011

The conversion of BaF2 thin films to BaO during deposition in an oxidizing ambient was investigated as a first step towards the in situ growth of superconducting thin films of YBa2Cu3Ox from Y, Cu, and BaF2 source materials. This conversion was found to occur at a temperature of 800 °C when BaF2 was evaporated in a partial pressure of H2O. The observed conversion temperature agrees well with an equilibrium thermodynamic model. Methods to reduce the growth temperature to the 600– 700 °C range are proposed.
Post-Newtonian expansion of an algebraically extended theory of gravity
Authors: Palmer J. H. , Mann R. B.
Published: April 2011

The post-Newtonian expansion is analyzed for an algebraically extended theory of gravity equivalent to a theory with a real, nonsymmetric metric, previously referred to as Algebraically Extended Hilbert Gravity (AHG). The hermiticity of the algebra-valued covariant and contravariant metrics is found to constrain the form of the expansion of the antisymmetric part of the real metric to one of two possibilities. Both of these display a qualitatively new technical feature: the lowest order equations are nonlinear, depriving the post-Newtonian expansion of its greatest asset. In one case, they lead to a solution with a negative Newtonian mass parameter. In the other case, they lead to a contact-type solution in which some metric components depend directly upon the stress–energy tensor rather than the integral of this distribution. The unphysical nature of these solutions rules out AHG as a physically viable alternative theory of gravitation.
Quantum fluctuations near a black-hole singularity embedded in an external field
Authors: Krori K. D. , Borgohain P. , Das(Kar) Dipali
Published: April 2011

In this paper we show, with two specific examples, that quantum fluctuations near a black-hole singularity embedded in an external field are independent of it, if it is a magnetic field but are not so if it is a gravitational field.
Born inversion of surface-scattered SAR (synthetic aperture radar) wave field
Authors: Moon Wooil M.
Published: April 2011

A new approach to synthetic aperture radar (SAR) digital image formation, based on inverse scattering theory, is derived as an alternative to the conventional method of imaging surface-scattered wave fields. The conventional image formation technique for high-resolution SAR data utilized azimuth compression using correlation in the range-Doppler domain. More recent approaches in SAR image formation algorithms exploit downward extrapolation of the wave field in the frequency–wavenumber (f–k) domain to perform not only the azimuth compression but also the range curvature correction at the same time, with improved quality of the final image. In this paper, imaging of the SAR wave field is formulated with the Born inversion approach, which includes a range-curvature-correction term that is valid at all ranges of image formation. This new inversion formula is established to exploit f–k domain computation, from which the complex backscattering coefficient, defined by the ratio of the backscattered wave field to the incident wave field, can be accurately estimated from the observed back-scattered wave field.
Molecular constants describing the transitions of 127,129I2 and 129,129I2
Authors: Gerstenkorn S. , Luc P. , Roy R. J. Le
Published: April 2011

Molecular constants describing the B–X absorption spectra of the radioactive species 127,129I2 and 129,129I2, are presented. Combined with previous results for the naturally occurring isotopomer 127,127I2, they provide the basis for a publicly accessible interactive computer program that automatically yields an ordered and assigned list of all transitions in a specified frequency range, together with the associated (predicted) Franck–Condon and Boltzmann factors.
Émission de rayonnement Lyman α dans les collisions H2 + H*(2s) aux énergies thermiques
Authors: Stern B.
Published: April 2011

The study made in Can. J. Phys. 68, 206 (1990) of the thermal-energy collision between H2 and metastable H*(2s), which could lead to the emission of Lyman α radiation, is reconsidered to take into account possible polarization effects. The total wave function of the system is expanded in terms of the molecular states of the intermediate complex [Formula: see text], which constitute the minimal basis of the four adiabatic states dissociating into H2 + H* (n = 2) where they are normally degenerate in energy. The results of the calculation show the existence, between three of those states, of average values of the separation distance R ([Formula: see text] atomic units) of long-range [Formula: see text] electronic interactions which depend on the geometric form of the [Formula: see text] molecule. From the molecular data the hypothesis of no longer considering H2 with H*(2s) as a rigid rotator is postulated and justified, after a purely quantum mechanical treatment of the radial equations, the mean ratio of the (oscillating) polarization angular differential cross sections to the elastic ones is found important [Formula: see text]. The inelastic phenomena are anticipated to be more marked in the ortho than in the para hydrogen at a low collision energy (75 meV).[Journal translation]
Magnetohydrodynamic transient-free convection flow past a semi-infinite vertical plate with constant heat flux
Authors: Gokhale M. Y. , Soundalgekar V. M.
Published: April 2011

A. magnetohydrodynamic transient-free convection flow of air past a semi-infinite vertical plate with a constant heat flux and a transversely applied uniform magnetic field is studied using the finite-difference method. The equations are solved by a computer using the Thomas algorithm. The transient temperature, transient velocity, average skin friction, and average Nusselt number are shown graphically. It is observed that the average skin friction and the average Nusselt number decrease owing to the application of the magnetic field. It also takes more time to reach a steady state when the magnetic field is present.