bluuebunny/crossref_metadata_2025 huggingface dataset:
The resonant scattering of gamma radiation from lead isotopes
Authors: Knowles J. W. , Khan A. M. , Mills W. F.
Published: April 2011

The scattering of gamma radiation from different isotopic mixtures of lead has been measured between 4.7 and 8.3 MeV with a variable energy beam with 175 keV resolution obtained by Compton scattering (n,γ) radiation of nickel from a curved aluminum plate. The elastically scattered radiation was detected with a 12.5 cm diameter, 12.5 cm long NaI(Tl) and with 27 or 49 cm3 Ge(Li) detectors located at scattering angles of 135° and 90°, respectively. Relative scattering measurements from targets of natural lead, radio-lead, and lead enriched in 208Pb show that the most prominent peaks of natural lead are in 208Pb at 7332.6 ± 1.3, 7087.7 ± 4.6, 7064.4 ± 3.5, 6721.0 ± 1.8, 5507.6 ± 1.8, 5292.6 ± 3.3, 4836.5 ± 4.6 keV. Measurements of resonant scattering and resonant self-absorption of the more intense scattered radiations provide information on level widths.
A microwave cavity measurement of collision-induced absorption in N2 and CO2 at 4.6 cm−1
Authors: Dagg I. R. , Reesor G. E. , Wong M.
Published: April 2011

Microwave cavity measurements have been extended to the 140 GHz or 4.6 cm−1 region. The details of the apparatus and method are presented. The techniques have been applied to the measurement of collision-induced absorption in N2 and CO2 at 295 K. The results are compared with measurements at lower microwave frequencies and also with far infrared measurements.
Collision-induced microwave absorption in Ne–Xe and Ar–Xe gaseous mixtures
Authors: Dagg I. R. , Reesor G. E. , Wong M.
Published: April 2011

Collision-induced microwave absorption has been observed at 4.4 cm−1 for the inert gas mixtures Ne–Xe and Ar–Xe. The absorption coefficient has been measured at room temperature for a range of density products up to 15 000 amagat2 and for different density ratios. The intracollisional absorption coefficient has been determined at this low frequency for each mixture from the data at low densities. These results for the absorption coefficient along with existing infrared results have yielded an accurate value for the zeroth moment for each of the spectra and hence improved values for the induced dipole moment parameters for the exponential model. For the range parameter, ρ, we obtain values of 0.312 Å and 0.408 Å, respectively, for the Ne–Xe and Ar–Xe mixtures. The values for the dipole strength parameters, μσ, calculated using the Lennard-Jones (12-6) potential are 0.0293 and 0.0328 D, respectively. Evaluations of μσ have also been carried out using other potentials. In particular, for Ne–Xe a value of μσ = 0.0377 D is calculated using the more realistic Morse – Spine – van der Waals (MSV) potential. At higher densities the results reveal intercollisional interference effects which result in a reduction of the absorption. The amount of reduction depends on the ratios of the gases in the mixture. In the highest density range studied, there is observed a marked increase in the absorption which may be attributed to many-body collisions.
The determination of solute atom displacements in mixed dumbbell interstitials for the face-centered-cubic lattice
Authors: Matsunami N. , Swanson M. L. , Howe L. M.
Published: April 2011

Interactions between irradiation-produced defects and solute atoms in metals have been investigated using the channeling technique. The interaction of interest in this investigation is the trapping of self interstitials by small solute atoms thus creating a [Formula: see text] mixed dumbbell, consisting of a host atom and a solute atom straddling a lattice site in the face-centered-cubic lattice. The displacement of solute atoms from lattice sites in the mixed dumbbell configuration was determined by comparing the experimentally observed normalized yields from solute atoms and from host atoms with the yields calculated analytically using the continuum approximation. The solute atoms in Al–Mn, Al–Cu, and Cu–Be mixed dumbbells were situated at 0.5 Å from the body-centered position, whereas the Ag atoms in Al–Ag dumbbells were 0.7 Å from this position. This result is consistent with the theoretical expectation that the smallest solute atoms are displaced the greatest amount in mixed dumbbells. In addition, experimentally obtained solute atom yields for [Formula: see text] and [Formula: see text] angular scans were compared with calculated scans. It was concluded that for large displacements of solute atoms into the flux peaking region, the analytical (continuum) calculation is a reliable method of determining solute atom displacements, either from the aligned yields or from the angular scans.
A note on the calculation of
Authors: Vallieres M. , Lie S. G. , Sprung D. W. L.
Published: April 2011

An expression for [Formula: see text] is derived and the approximations made by previous authors noted. It is found that previous calculations have overestimated [Formula: see text] by about a third, due to neglect of pairing contributions.
An improved gravitational formalism
Authors: Rastall Peter
Published: April 2011

In earlier papers, a theory of gravity was developed in which the space-time metric depends on a unit vector field and a scalar potential. The formalism becomes much simpler if one uses just a vector field. The theory is equivalent to a special case of the earlier one.
Attenuated total reflection angular spectra of a Ag film bounded by dielectric slabs
Authors: Kovacs G. J. , Scott G. D.
Published: April 2011

Optical excitation of both the symmetric and antisymmetric surface plasma waves (SPW) of a plasma layer has been observed in the p-polarized attenuated total reflection (ATR) angular spectra of a three film system (cryolite–Ag–cryolite) evaporated onto the base of a glass prism. The relative strengths of the two SPW reflectance resonances depend on the thicknesses of the cryolite films. In addition the ATR spectra of both p- and s-polarizations contain resonances due to excitation of guided light modes localized in the second dielectric layer, and the progression of the guided mode resonances is studied in transmittance as well as reflectance. Detailed calculations of the Poynting vector field help in understanding discrepancies between theory and experiment thought to be due largely to optical inhomogeneities of the cryolite films. A simple model of thin cermet layers at the metal–dielectric interfaces accounts qualitatively for the observed discrepancies in position and intensity of the resonances.
Functional derivatives for the critical magnetic field of Pb
Authors: Daams J. M. , Carbotte J. P.
Published: April 2011

We have calculated for superconducting Pb in the dirty (isotropic) limit the following functional derivatives: δTc/δα2F(ω), δHc(0)/δα2F(ω), δD(t)/δα2F(ω), ∂Tc/∂μ*, ∂Hc(0)/∂μ*, and ∂D(t)/∂μ*, where Tc, Hc(0), D(t), t, α2(ω)F(ω), and μ* are, respectively, the critical temperature, critical field at T = 0, deviation function for the critical field, reduced temperature T/Tc, electron–phonon spectral density, and Coulomb repulsion parameter. Our values for the first two functional derivatives are in good agreement with previous work by Rainer and Bergmann. We present the others here for the first time to relate the observed changes in Tc, Hc(0), and D(t) under hydrostatic pressure to the change in α2(ω)F(ω) and μ*.
Binary encounter calculations on electron impact double ionization of noble gas atoms
Authors: Kumar A. , Roy B. N.
Published: April 2011

Electron impact double ionization cross sections of noble gas atoms have been calculated in the binary encounter approximation by using Gryzinski's double binary encounter model. The correct expression for σΔE including exchange and interference as given by Vriens has been used. Hartree–Fock and hydrogenic velocity distribution functions have been used in considering the ejection of the first and the second atomic electron, respectively. Contribution of ionization from inner-shell has also been taken into account. Calculated values of cross sections are found to be in agreement with the experimental observations.
A modified dispersion equation for drift dissipative instabilities in a weakly ionized plasma
Authors: Mah S. Q.
Published: April 2011

A third degree dispersion relation for drift dissipative instabilities in a weakly ionized plasma is derived. As opposed to previously derived dispersion relations, no assumption as to the magnitude of the ion cyclotron frequency with respect to the drift frequency is made. Sample numerical solutions for this equation are given for various choices of plasma parameters.
Holtsmark electric field distributions and associated broadening effects due to charged defects in crystals
Authors: Taylor D. R.
Published: April 2011

Low concentrations of charged defects in crystals generate random electric fields characterized by Holtsmark distributions. In descriptions of the electric field broadening and splitting of ionic energy levels in various crystal symmetries, three distributions are frequently applicable: that for the magnitude of the local electric field, that for the planar component of the electric field perpendicular to a high-symmetry axis, and that for the component parallel to a high-symmetry axis. Expressions are derived for these distributions by generalizing earlier results for isotropic media, and series expansions and polynomial approximations are given to facilitate their use. A range of examples are described to illustrate electric field splitting of electronic levels and effects on low temperature properties.
Comparison of multiple scattering approximations in a three body problem
Authors: Kulhar V. S. , Jain A. K. , Shastry C. S.
Published: April 2011

An analysis of the nonrelativistic quantum mechanical problem of three particles of equal mass interacting via attractive delta function potentials in one dimension is carried out. Following the methods of McGuire and Dodd with two body potentials of equal strength, exact matrix elements for the process of elastic and rearrangement scattering are rederived and some mistakes occurring in their papers have been corrected. Then expressions are obtained for transition matrix elements for these processes in the first order using Newton, Born, Newton–Faddeev, and Lovelace–Faddeev formulation. Numerical results obtained are compared with the exact results. It is found that above breakup threshold the Newton–Faddeev scheme gives better results in comparison to other schemes for elastic as well as rearrangement scattering. Thus, this paper provides us with a comparative analysis of several multiple scattering expansions available in the literature.
Finite frequency ultrasonic attenuation in an anisotropic superconductor
Authors: Hong K. M. , Carbotte J. P.
Published: April 2011

The ultrasonic attenuation of an isotropic superconductor shows a finite jump at a frequency of twice the energy gap because of the onset of pair breaking. For an anisotropic superconductor it is shown that the rise in attenuation proceeds in steps when there exist regions on the Fermi surface with distinct gap values separated by a finite amount.
M-dependence of collisional transfer of rotational energy in methyl alcohol: the (4−1 ← 30)p – (40 ← 31)s system
Authors: Lees R. M.
Published: April 2011

An M-resolved microwave double resonance study of collision-induced rotational energy transfer has been carried out for the (4−1 ← 30)p – (40 ← 31)s four-level system of CH3OH. Spectra are reported for each distinct combination of pump and signal M-components. The observed M-dependence of the double resonance signals is in good agreement with a very simple model of the collisional transfer in which a transition rate constant is taken to depend only on the square of the dipole matrix element for the transition.
The role of the ordinary and anharmonic Raman processes in Rb2PtI6
Authors: McElroy Robert G. C. , Armstrong Robin L.
Published: April 2011

Measurements of iodine nuclear spin lattice relaxation in Rb2PtI6 provide a rare opportunity to directly measure the separate contributions of the ordinary and anharmonic Raman processes. It is shown that for this crystal one may separately determine W1 and W2 and that these rates may be uniquely related to the two Raman processes. The experimental results show that the anharmonic Raman process is dominant but not to the total exclusion of the ordinary Raman process.
Optical measurement of post discharge density perturbations
Authors: Tulip John , Faszer Wayne , Seguin Herb
Published: April 2011

An optical method which relies upon the deflection of a He–Ne laser is used to measure gas density perturbations following a pulsed discharge. The damping time of these perturbations for a discharge in an open flow duct is400 μs, showing that the maximum repetition rate for a discharge free of perturbation is about 1 kHz. The density wave character immediately after the discharge is described.
Electroionization of D2O and H2O and study of fragments H+ and OH+
Authors: Lefaivre D. , Marmet P.
Published: April 2011

In the electroionization efficiency curve of H2O and D2O, clearly resolved newly observed structures converging to the (1b2) and (2a1) limits are reported and interpreted between threshold and 31 eV. A perturbation from the OH+ + H + 2e dissociation continuum is observed in the ionization efficiency curve of H2O. Appearance curves of H+ from H2O are analysed and the presence of ion pair formation H+ + OH− at threshold is demonstrated. Observation of these structures reveals new information on the mechanism of electron impact on molecules.
Raman scattering from impurities in nonmetals. II. Anharmonic effects
Authors: Chow H. C.
Published: April 2011

Anharmonic effects on the impurity Raman spectrum are examined on the basis of an approximately derived, nonphenomenological Raman spectrum function. It is shown that owing to the phonon life-time effect, anharmonicity broadens the zero-phonon Raman line and the accompanied satellite phonon Raman lines. The case of resonant scattering is re-examined and the result suggests that the dipole radiation formulation of Raman scattering, which is the basis of the present and some other treatments, is unsuited for demonstrating hot luminescence.
Rotation induced electromotive forces in normal and superconducting metals
Authors: Blackford B. L. , Calkin M. G. , Purcell A. J. , Purcell C. J. , Stroink G.
Published: April 2011

The theory of rotation induced emfs in normal and superconducting metals is discussed and we describe the results of an experiment designed to measure such emfs. We show that for a normal rotor connected via superconducting sliding contacts to a stationary external circuit the expected emf is mν2/e, twice what one might expect on the basis of simple calculations, whereas for superconducting rotors the expected emf is zero. An attempt was made to detect the predicted rotation induced emf due to a normal rotor and to put an upper limit on the emf generated by a superconducting rotor. In both cases, superconducting sliding contacts were used to connect the centre to the rim of the rotating cylinder with a Clarke SLUG, used as a galvanometer. The observed emfs, although extremely small by ordinary standards, were several orders of magnitude larger than predicted and appeared to be an artifact generated by the sliding contacts.
Rotational analysis of the A2Σ+–X2Σ+ transition of 27Al80Se
Authors: Lavendy H. , Pinchemel B.
Published: April 2011

High resolution emission spectra of the A2Σ+–X2Σ+ system of 27Al80Se have been obtained from a 'composite wall' hollow cathode in the 3700–4700 Å region. Vibrational, rotational, and spin–rotation constants have been determined.
Systematics for the Z1-oscillation in stopping powers of various solid materials
Authors: Ward D. , Andrews H. R. , Mitchell I. V. , Lennard W. N. , Walker R. B. , Rud N.
Published: April 2011

Stopping powers have been measured at common ion velocities v = 0.18 cm ns−1 (v/v0 = 0.82) and v = 0.22 cm ns−1 (v/v0 = 1.01) for all projectiles 6 ≤ Z1 ≤ 20 in five solid materials: carbon, aluminum, nickel, silver, and gold. The Z1-oscillation was observed and several new features for the systematics of the oscillation emerge: (i) the amplitude of the oscillation varies with target material and is weak in nickel, (ii) the amplitude changes with ion velocity but this dependence varies with material, (iii) the phase of the oscillation varies by up to 2 units in Z1 according to the material, and (iv) the phase is independent of the velocity over the range studied.We conclude that at low velocity the effect of projectile (Z1) electronic structure on the stopping power cannot be separated from that of the material (Z2).An apparent variation of the stopping power with target thickness was observed and is interpreted in terms of multiple scattering through a recent theoretical treatment.
Lifetime of the 5p2lD2 level of neutral strontium
Authors: Kelly F. M. , Mathur M. S.
Published: April 2011

The lifetime of the 5p21D2 level of neutral strontium has been determined to be 9.53 ± 0.10 ns by a Hanle effect experiment using excitation by the line at 6550 Å from the 5s5p1P1 excited level of neutral strontium. No dependency of the lifetime on the density of neutral atoms was detected.
Dependence of radio aurora at 398 MHz on electron density and electric field
Authors: Moorcroft D. R.
Published: April 2011

A statistical study has been made of the dependence of radio-auroral echoes obtained with the 398 MHz radar at Homer, Alaska on electric fields and election densities measured simultaneously with the Chatanika incoherent scatter radar. There is a dependence on the magnitude of the electric field which is consistent with a threshold electric field of about 23 mV/m. The results of the analysis have been compared with the predictions of several existing theories of radio aurora. The echoes apparently arise from secondary irregularities generated by a primary two-stream instability; it is most likely that secondary two-stream irregularities are involved. Many of the data were obtained when the electric field was directed southward, and during this time the radio-auroral echoes were found to come from heights at or below the height of the maximum E-region electron density. Surprisingly, no echoes were obtained for large electron densities, regardless of the strength of the electric field. This implies that the spatial anticorrelation between visual and radio aurora involves more than the reduction of the electric field within visual forms.
The A–X system of the I2 molecule
Authors: Ashby R. A.
Published: April 2011

The A3Π1u–X1Σg+ system of the I2 molecule, lying in the 9600–8000 Å region, has been photographed in absorption under conditions of high dispersion. The band origins and B′ values of 18 bands in the lengthy progressions based on ν″ = 4 and 5 have been determined. By assuming that the potential curve of the A state is a Morse curve, an estimate of the vibrational numbering of this state has been made. Based on this numbering estimates of important constants of the A3Π1u state have been achieved: viz., Te = 11 059 cm−1, De = 1488 cm−1, ωe = 95.9 cm−1, Be = 0.02817 cm−1, and re = 3.071 Å. A comparison between the A state and the lower state of the ultraviolet laser transitions of the I2 molecule, based on the values of the constants De, ωe, xeωe, and yeωe, shows that the A state cannot be the lower state of the laser transitions.
Rocket attitude determination by a Fourier method
Authors: Green D. W. , Wilson B. G.
Published: April 2011

It is shown that the parameters completely specifying the angular motion of a symmetrical sounding rocket in torque-free flight may in general be determined from a Fourier-transformed segment of transverse-axis magnetometer data, with limited additional data from an auxiliary optical sensor. The method is simple and rapid, and an example is worked out.
Elastic scattering of 29 MeV negative pions from 208Pb
Authors: Johnson R. R. , Marks T. , Masterson T. G. , Bassalleck B. , Erdman K. L. , Gyles W. , Gill D. , Sabev C.
Published: April 2011

We have measured the differential cross section for 29 MeV negative pions elastically scattered from 208Pb. Range telescopes were used to detect the scattered pions. The data are compared with calculations of Rost.
Weak interaction effects in low energy pion photoproduction
Authors: Woloshyn R. M.
Published: April 2011

Weak interaction induced parity-violating asymmetries in low energy pion photoproduction are calculated to be of order 10−7. The problem of isolating the weak neutral current dominated pion–nucleon coupling is discussed.
The A–X system of the CuI molecule
Authors: Mishra G. P. , Rai S. B. , Upadhya K. N.
Published: April 2011

The spectrum of the A–X system of the CuI molecule has been reinvestigated by photographing it in the second order of a 10.6 m concave grating spectrograph. It is found that the assignments of the transition by Wu and Dows to be A1Σ–X1Σ is incorrect and it should be A1Π–X1Σ in agreement with Pandey, Upadhya, and Mohanty. Some modifications have been suggested over the analysis given by Pandey et al.
Density dependence of the Hanle effect of the 3s4p1P10 level of neutral magnesium
Authors: Kelly F. M. , Mathur M. S.
Published: April 2011

The Hanle effect in the 3s2 1S0–3s4p1P1 (2026 Å) transition of Mg I has been studied over a range of densities. The low density observations lead to an accurate lifetime measurement of the 4p1P1 excited level. Related oscillator strengths are calculated.
Correlation between the sea level muon spectrum and the primary nucleon spectrum using the Cocconi–Koester–Perkins model
Authors: Chakrabarti A. K. , Das A. K. , De A. K.
Published: April 2011

Using the recent ISR data of proton–proton interactions on the inclusive production of pions and nucleons, realistic values of the mean pion inelasticity Kπ and the mean nucleon inelasticity KT have been estimated. These values have been used for the derivation of the sea level differential muon spectrum from the primary nucleon spectrum and vice versa using the CKP model as an extension of the work presented in an earlier article. It is found that none of the measured primary nucleon spectra of Ryan, Ormes, and Balasubrahmanyan and Grigorov, Rapoport, and Shestoperov fit any of the precisely measured muon spectra of Ayre, Baxendale, Hume, Nandi, Thompson, and Whalley and Allkofer, Carstensen, and Dau in spectral shape or the absolute value. On the other hand good agreement between the derived muon spectra and the spectra of Allkofer et al. and Ayre et al. is found if the primary nucleon spectra of the forms, N(Ep) = (1.38 ± 0.08)Ep−2.59 and N(Ep) = (1.00 ± 0.10)Ep−2.55, respectively, are assumed. The first form is comparable with that obtained by Brooke, Hayman, Kamiya, and Wolfendale following more approximate but similar procedure. It is also not unjustified when compared with the measured primary all nuclei spectrum of Grigorov et al. in the light of suggestions made by Ellsworth, Ito, Macfall, Siohan, Streitmatter, Tonwar, Vishwanath, Yodh, and Balasubrahmanyan. By comparing the pion production spectra derived from the same primary nucleon spectrum but using the CKP and the scaling models, it is concluded that the results are sensitive to the model assumed for the collisions.
Lattice heat capacity, third-order elastic constants, and thermal expansion of scandium
Authors: Rao R. Ramji , Rajput A.
Published: April 2011

The lattice heat capacity, third-order elastic constants, and thermal expansion of the hexagonal-close-packed rare-earth metal scandium are worked out using an approach proposed by Keating. The calculated third-order elastic constants are utilized to investigate the temperature dependence of the bulk modulus and the pressure variation of the lattice parameters of this metal using, respectively, Anderson's theory and Thurston's extrapolation formulae. The available experimental data compare well with the corresponding theoretical results.
Thermal depolarization in crystals of CaF2:Na+, SrF2:Na+, and BaF2:K+
Authors: Ong S. H. , Jacobs P. W. M.
Published: April 2011

The defect complexes formed when the univalent metal ions Na+ or K+ are incorporated in CaF2, SrF2, or BaF2 have been investigated by the technique of thermal depolarization. Only a single depolarization event is found in CaF2:Na+ and SrF2:Na+ and this is ascribed to nearest neighbour Nas+Fv− complexes (s = substitutional ion, v = vacancy). Evidence for this kind of complex is also observed in BaF2:K+ and a second depolarization peak at 138 K in these crystals is attributed to an M+ impurity.
On nuclear spin statistics in rotational transition intensities in tetrahedral AB4 molecules
Authors: Rosenberg Arieh , Susskind Joel
Published: April 2011

A general expression is derived for the integrated intensity of rotational transitions in the vibronic ground state of tetrahedral molecules, taking into account the nuclear spin statistics. It is shown that the ratio of this expression to previously published spin-free integrated intensities depends only on the tensor character N of the operator driving the transition, the appropriate rotational quantum numbers J and J′, and the nuclear spin IB of the identical nuclei. Tables are given for N = 3, 4 and J ≤ 50 which enable the calculation of integrated intensities for octopole and hexadecapole collision induced dipole moment transitions, centrifugal distortion induced dipole moment transitions, and centrifugal distortion induced anisotropic polarizability tensor Raman transitions. It is shown that the relative error of the spin-free integrated intensity calculation is proportional to (2IB + 1)−2.
The effect of a general oblique magnetic field on Rayleigh–Taylor instability
Authors: Ariel P. D. , Aggarwala B. D.
Published: April 2011

The effect of a general oblique magnetic field on the development of Rayleigh–Taylor instability has been investigated. It has been demonstrated that n2 is purely real, where n is the growth rate of disturbance. Also in this case, the solution is characterized by a variational principle. The exact solution for the case of two superposed fluids has been derived when the oblique magnetic field is constant. It is shown that when the lighter fluid is topped by the heavier fluid a mode of maximum instability exists if the ratio of horizontal to vertical magnetic field is sufficiently large. No normal mode solution is possible if the lighter fluid lies atop the heavier fluid. Use has been made of variational principle to obtain the approximate solution of a fluid having exponentially varying density. It is found that for some disturbances, the oblique magnetic field has a greater stabilizing influence compared to a horizontal or vertical magnetic field of the same strength.
Midsummer stratospheric NO2 at latitude 45°S
Authors: Harrison A. W.
Published: April 2011

Ground based measurements of stratospheric nitrogen dioxide during morning and evening twilight have been made at Lauder, New Zealand, 169°40′E longitude and 45°04′S latitude during January and February 1979. The analysis shows that ozone absorption overlying the nitrogen dioxide absorption bands cannot be ignored. After correcting for ozone absorption the mean vertical column abundance of nitrogen dioxide was found to be 2.9 × 1015 cm−2 (evening, solar zenith angle = 90°) and 1.1 × 1015 cm−2 (morning, solar zenith angle = 90°).
Particle aspect analysis of electromagnetic ion cyclotron instability
Authors: Misra K. D. , Tiwari M. S.
Published: April 2011

The electromagnetic ion cyclotron instability, incorporating the details of charged particles trajectory, has been discussed. The wave is assumed to propagate along the ambient magnetic field in an anisotropic plasma. The plasma is considered to consist of resonant and non-resonant particles. Here it is assumed that resonant particles participate in energy exchange with the wave whereas the non-resonant particles support the oscillatory motion of the wave. Growth rate has been obtained by an energy conservation method for an arbitrary velocity distribution function. The effect of non-resonant particles on the resultant growth rate has also been discussed. The maximum growth rate has been evaluated for various values of β (ratio of kinetic pressure to magnetic pressure) and [Formula: see text]. The marginal stability criterion has also been derived. The time development of the ion cyclotron instability and the change in the resonant particles energy have been computed for magnetospheric plasma.
Generalized Moshinsky bracket recurrence relations
Authors: Bevelacqua J. J.
Published: April 2011

Recurrence relations for generalized Talmi–Moshinsky brackets are derived. These relations permit the generation of transformation brackets once appropriate starting brackets are determined. The savings in computer time, when compared with generating brackets individually, is at least a factor of 10 for brackets with radial quantum numbers as large as 9 and angular quantum numbers as large as 2.
Broken SU(6)w analysis of electroproduction
Authors: Avilez Clicerio , Cocho Germinal
Published: April 2011

Assuming broken SU(6)w, an analysis of electroproduction of resonances in the second and third zones is carried out. Deep inelastic inclusive cross sections are written as a sum of s-channel resonances, and the results compared with the resonance analysis. Supporting the assumption, a rather different Q2 dependence is found between transitions to resonances with [Formula: see text] and [Formula: see text]. This broken spin W analysis suggests a two component picture of deep inelastic scattering.
A theoretical study of the B′2Σ+–X2Σ+ band system in MgH and MgD
Authors: Sink M. L. , Bandrauk A. D.
Published: April 2011

Ab initio Cl calculations of the transition moment for the B′2Σ+–X2Σ+ transition in MgH are reported. Theoretical values for the Franck–Condon factors, band strengths, band oscillator strengths, and transition probabilities have been computed for MgH and MgD. An analysis of our results for this system predicts many bands to be observable which have not yet been identified. Dipole moment functions and vibrationally averaged dipole moments are given for the X2Σ+, A2Π, and B′2Σ+ electronic states.
The magnetic rotation spectrum of formaldehyde: singlet–triplet perturbations in the 41 and 43 levels of the Ã1A2 state of H2CO
Authors: Ramsay D. A. , Till S. M.
Published: April 2011

A survey of the magnetic rotation spectrum (MRS) of formaldehyde in the near ultraviolet is reported. The [Formula: see text] and [Formula: see text] bands of the [Formula: see text] system are also studied under high resolution. The rR and pP branches of these bands are found to be active and it is noted that the intensities appear to increase more rapidly with increasing Ka in the MRS than in the absorption spectrum. The 43 and 61 levels are in Coriolis interaction at higher Ka values, and some rR branches of the [Formula: see text] band are identified.Several strong lines in the MRS are shown to be associated with rR, rP, pR, and pP lines in the absorption spectrum and to reveal the presence of singlet–triplet perturbations. Only one perturbed rotational level is found in the [Formula: see text] band, but for the [Formula: see text] band several rotational levels are found to exhibit such perturbations, e.g. 190,19, 191,19, 171,16, 102,8, 102,9, 112,9, 173,14, 173,15, 183,15, and 183,16. These perturbations are produced by ΔJ = ΔN = ΔKa = 0 interactions with the 415161 level of the ã3A2 state and by ΔJ = ΔN = 0. ΔKa = ± 1 interactions with the 5161 level. The matrix elements are of the order of 0.01–0.10 cm−1.
Mean field theory of the orientational properties of (J = 1) hydrogen molecules on the surface of Grafoil
Authors: Harris A. B. , Berlinsky A. J.
Published: April 2011

A mean field theory is developed which is applicable to the orientational behavior of (J = 1) hydrogen molecules on the surface of Grafoil. The hydrogen molecules are assumed to form a triangular lattice in a weak, axially symmetric crystal field, Vc. perpendicular to the substrate and to interact via the electric quadrupole–quadrupole interaction with nearest-neighbor coupling constant Γ. Free energy calculations for the various possible ordered phases are presented, and a Landau expansion is used to investigate the phase boundary between the disordered and ordered phases. A computer calculation, based on the iterative method of James, is used to determine the lines of transition between ordered phases. For almost all values of Vc < 22.5Γ, the disordered to ordered state phase transition is continuous. Four distinct types of ordered phases are found — a four-sublattice phase, two two-sublattice phases, and a one-sublattice phase which resembles an X–Y model. Comparison is made to the recent nmr data of Kubik and Hardy for H2 and D2 on Grafoil.
Enhanced plasma losses due to collisional drift waves and their reduction by dynamic stabilization in a weakly ionized plasma
Authors: Mah S. Q. , Andel H. W. H. Van
Published: April 2011

The mechanism of anomalous plasma transport associated with dissipative drift instabilities in a weakly ionized plasma is investigated experimentally. Detailed measurements of the phase difference between electron density and potential fluctuations are presented. The results show good agreement between predicted anomalous losses associated with this phase difference and measured reductions in the plasma density. It is shown experimentally that dynamic stabilization using an oscillating azimuthal magnetic field effectively reduces the plasma losses due to the fluctuations.
High temperature absorption on the P(26)–P(32) CO2 laser transitions
Authors: Robinson A. M.
Published: April 2011

The line-center absorption coefficient of CO2, has been measured as a function of temperature from 295 to 650 K for the P(26)–P(32) laser transitions.
The harmonic oscillator approximation to the density matrix
Authors: Bhaduri R. K. , Zaifman L. F.
Published: April 2011

The density matrix expansion for a system of nucleons moving in an isotropic harmonic oscillator potential is derived. This series is assumed to be a good approximation for the angle averaged density matrix of spherical nuclei, and is summed under a certain approximation. The form proposed by Campi and Bouyssy is obtained in our model as a special case. Other alternative forms are proposed and numerical comparisons are made using the Skyrme-III force.
Random walk and SU(2) Clebsch–Gordon coefficients
Authors: Lemire F. , Patera J.
Published: April 2011

This article contains a new interpretation of the values of the SU(2) Clebsch–Gordon coefficients (CGC). It is shown that a given CGC C(l1,l2,l;m1,m2,m) can be understood as a transition function for a random walk on a two dimensional lattice between the origin and the point (m1,m2) in l1 + l2 + l steps. This interpretation is based on the generating function for the CGC which has previously been shown to be a rich and concise source of information on the CGC.
Comparison of radio-auroral spectral characteristics at 398 MHz with incoherent scatter measurements of electric field
Authors: Moorcroft D. R.
Published: April 2011

Radio-auroral Doppler measurements obtained with the 398-MHz Homer phased-array radar were compared with simultaneous and coincident measurements of electron density and electric field made by the Chatanika incoherent scatter radar. The results for this post-midnight period of observation are not consistent with a direct relationship between the radio-auroral Doppler velocity and the line of sight component of the electron drift velocity, in contrast to the previous observations at VHF. Instead, the observations are consistent with the hypothesis that the echoes arise from the two-stream/drift-gradient irregularities traveling at their threshold phase velocities, close to the local acoustic velocity, Cs. Some of the Doppler velocities observed are considerably less than Cs, and may indicate propagation away from perpendicular to the magnetic field, possibly resulting from magnetic field line distortion.
Optical absorption of Cu2O in the near infrared and the role of metallic inclusions
Authors: Weichman F. L. , Reyes J. M.
Published: April 2011

We have measured the optical absorption characteristics of copper oxide single crystals in the range from 1.1 to 2.0 eV. The crystals were annealed at various oxygen pressures at high temperatures and quenched to room temperature. A major, broad, previously unknown absorption peak was found at 1.6 eV which we relate to the formation of copper inclusions in the oxide. Although experimental data on thin copper films agree with our assumptions, we cannot reconcile our results with scattering theory of small metal spheres embedded in a dielectric. Agreement between scattering theory and optical absorption may be achieved for nonspherical particles for which as yet no other experimental evidence exists.
Electrical properties of MEM(TCNQ)2
Authors: Morrow M. , Hardy W. N. , Carolan J. F. , Berlinsky A. J. , Weiler Larry , Gujral V. K. , Janossy A. , Holczer K. , Mihlay G. , Grüner G. , Huizinga S. , Verwey A. , Sawatsky G. A.
Published: April 2011

Detailed studies of the dc and microwave conductivity and dielectric constant of the quasi-one-dimensional conductor, MEM(TCNQ)2 for 4.2 K < T < 360 K are presented. Particular attention is paid to the strong first-order transition at 335 K where the conductivity jumps by about three orders of magnitude on heating and the activation energy for the conductivity disappears. These electrical data are compared to previously published magnetic susceptibility measurements and to recent structural, heat capacity, and nmr data. The role of Coulomb interactions, in determining the temperature dependence of the conductivity, the susceptibility, and the structure, is emphasized.
Lattice dynamics of ZnTe, CdTe, GaP, and InP
Authors: Kushwaha M. S. , Kushwaha S. S.
Published: April 2011

An eight-parameter bond-bending force model (BBFM), recently developed by us for zinc-blende (ZB) structure, has been used to study the lattice dynamics of other compounds of the II–VI and III–V groups. The model parameters were calculated using six critical point phonon frequencies, two elastic constants, and the lattice equilibrium condition. Phonon dispersion curves, phonon density of states, and Debye-characteristic temperatures have been calculated. The comparison of theoretical and the available experimental results reveals a fairly good agreement. The merits and demerits of the present model have been discussed in full.
Calculation of desorption times using local or nonlocal surface potentials
Authors: Gortel Z. W. , Kreuzer H. J. , Teshima R.
Published: April 2011

The desorption times of a gas desorbing from the surface of a solid in localized physi-sorption are calculated in a quantum statistical theory based on either a local surface potential or its nonlocal approximation. A detailed comparison of the two approaches shows reasonable agreement.
Debye–Waller factor and the Lindemann parameter of some hexagonal close-packed metals
Authors: Ramanand A. , Rao R. Ramji
Published: April 2011

The Debye–Waller factor has been calculated as a function of temperature for the four hexagonal close-packed (hcp) metals cobalt, ruthenium, erbium, and scandium, using a lattice-dynamical model to evaluate the normal mode frequencies and eigenvectors in the harmonic approximation. The calculation of the anisotropic temperature factors for these metals requires a knowledge of the eigenvectors for the various normal modes of vibration. The frequency distribution function is also used to calculate the mean-square amplitude of displacement of the atoms, in the cubic approximation. The first and second negative moments of the distribution function are used to calculate the low- and high-temperature limits of [Formula: see text], respectively. The value of the Lindemann parameter obtained from the present calculations is consistent with the value quoted by Gschneidner.
An energy equivalent for viscous dissipation of atmospheric disturbances
Authors: Salby Murry L.
Published: April 2011

A means of representing the effect of viscous diffusion comprehensively for both horizontally and vertically propagating atmospheric waves is developed. This is accomplished by replacing the viscous diffusion terms in the momentum equations by a different damping mechanism, here, heat loss in the thermodynamic equation. The particular form of the artificial damping is chosen so that it reproduces the dissipation due to the original damping. Results obtained here are directly applicable to inhomogeneous basic states and evanescent waves. Solutions for the isothermal case display the same character as those for the idealized fully viscous problem examined by Yanowitch.
A study of the extended-ion model for F centers in alkali halides
Authors: Leung C. H. , Song K. S.
Published: April 2011

The extended-ion model in the calculation of the electronic structure of simple defects in ionic crystals is studied with the example of the F center in LiF. An efficient scheme of computation is set up in which orthogonalization of the defect wave function to the core orbitals and the exchange terms between the defect and the core electrons are treated exactly for a large enough number of shells around the defect. This is made practical by a systematic use of lattice harmonics and Gaussian-type orbitals. The effect of using different sets of core orbitals in the extended-ion model calculation is studied next. It is found that the results are quite sensitive to the choice of core orbitals. It is pointed out that as anions undergo contraction and cations expansion in an ionic lattice, this effect should be taken into account in an extended-ion model work by employing appropriate ionic orbitals.
Simultaneous Wiener–Hopf equations
Authors: Rawlins A. D.
Published: April 2011

In Noble's book The Wiener Hopf Technique, Pergamon, 1958, he considers the coupled system of Wiener–Hopf equations (§4.4, pp. 153–154)[Formula: see text]He shows that provided the functions L(α), M(α), Q(α), and R(α) have only simple pole singularities the solution can be reduced to two sets of infinite simultaneous linear algebraic equations. In this article a different approach is used which gives the solution in the form of a Fredholm integral equation of the second kind. This Fredholm integral equation can be reduced to infinite sets of simultaneous linear algebraic equations under the less restrictive conditions that either (i) L(α)/M(α) has no branch points in the lower α-half plane: Im(α) < τ+; or (ii) Q(α)/R(α) has no branch points in the upper α-half plane: Im(α) > τ−. In the special case considered by Noble if L(α)/M(α) (or Q(α)/R(α)) only have simple poles in the lower (upper) half plane then the Fredholm integral equation reduces to one infinite set of simultaneous equations. This extends the Wiener–Hopf technique to yet a larger class of boundary value problems, and simplifies the numerical computations.
Triple Pomeron coupling and pion inclusive scattering
Authors: Migneron R. , Robinson J. L.
Published: April 2011

A characteristic rise in the cross section near x = 1 has been reported for the single particle inclusive reaction π−p → π−X at Fermilab energies. Factorizable Regge amplitudes are used with a well-established analysis of the pp → pX peak to construct a parametrization of the triple-Regge couplings with αP(0) > 1 and to give a triple-Regge description of the meson + proton → meson + X cross section. Good agreement with the π−p → π−X data at 147 GeV/c is obtained and the peak is dominated by the triple-Pomeron component. This approach provides a reliable method for obtaining an estimate of the non-diffractive component. The inelastic diffractive cross section rises with energy and is found to account for most of the observed rise in σtot(π±p). The procedure is extended to K±p → K±X.
Experimental determination of the dilational strain dependence of the Fermi surface of white tin
Authors: Mak D. K. , Perz J. M.
Published: April 2011

The derivatives with respect to uniaxial elongational strain of the areas of representative orbits on all sheets of the Fermi surface of tetragonal white tin have been deduced from simultaneous measurements of the Landau quantum oscillations in elastic moduli and in torque. Strain derivatives have been determined for most known extremal cross-sectional areas normal to the [100], [110], and [001] symmetry axes; the anisotropy of the strain derivatives of several area branches, having normal directions in the (010) and (001) planes, has also been studied. Uniaxial and hydrostatic stress derivatives deduced from the strain derivatives have been found to be generally consistent with values obtained by other means.
Semiempirical prediction of electron affinities
Authors: Fraga Serafin
Published: April 2011

The electron affinities of the elements H through Ar have been obtained within the framework of a new semiempirical procedure. The agreement between the predicted and the presently accepted values suggests that the method may be of use in estimating the electron affinities of other elements.
The asymptotic vacuum and soliton sector wave functionals
Authors: Ragiadakos Ch.
Published: April 2011

Using a variant of the Creutz quantization method we find in the field representation the wave functionals of the "in" vacuum and soliton sector states. The quantum stability of the different vacuum sectors is explicitly proved.
An efficient method for fitting theoretical profiles to small structures superimposed on large nonlinear backgrounds
Authors: Marchand P. , Boulet G.
Published: April 2011

An efficient method by which the coefficients of theoretical profiles of a single variable may be extracted from small experimental profiles superimposed on large nonlinear backgrounds is described. Several digital high-pass filtering methods are discussed and compared.
The Abraham force: comments on two recent experiments
Authors: Lorrain Paul
Published: April 2011

The Abraham force is discussed briefly. It is recalled that the old controversy concerning the Minkowski and Abraham tensors for an electromagnetic field in matter, as well as efforts at observing the Abraham force, are pointless because it is now well established that both tensors are equally satisfactory, as long as the various subsystems are treated correctly. If one ascribes to the electromagnetic field in matter a momentum density of E × H/c2, like Abraham, then Lahoz and Graham have observed the magnetic force density on a polarization current, or only one of the six components of the Abraham force. Their interpretation of their experiments is erroneous.
The effects of modulation frequency and rf ENDOR power on 53Cr3+ ENDOR lines in CsAl sulfate alum
Authors: Manoogian A. , Chan B. W.
Published: April 2011

An investigation was made of the effects of modulation frequency and rf ENDOR power on the single and double quantum ENDOR spectral lines of 53Cr3+ ions in single crystals and powders of CsAl sulfate alum. Measurements were made of the linewidths and intensities in the single crystals and of the linewidths in the powders. It was found in the single crystals that a factor of 2/1 exists for the ratio of single/double quantum linewidths at the limit of zero ENDOR power and modulation frequency. Interpretation of the line intensity results with the results of lineshape theory indicates that the ENDOR lines are of Lorentzian form, at least for low values of ENDOR power.
A complete set of irreducible isotropic tensors of rank six
Authors: Eu Byung Chan
Published: April 2011

A complete set of irreducible isotropic tensors of rank six is presented which is obtained by the parentage scheme. The set is more compact in form than the available set in the literature and the symmetry properties of elements are transparent.
Density dependence of the Hanle effect of the 4s4p1P1 level of neutral calcium
Authors: Kelly F. M. , Mathur M. S.
Published: April 2011

The Hanle effect in the 4s21S0–4s4p1P1 (4226.7 Å) transition in Ca I has been observed over a wide range of densities. The low density observations determine the lifetime of the 1P1 level to be 4.49 ns. Collision parameters are obtained from observations in the high density region.