bluuebunny/crossref_metadata_2025 huggingface dataset:
On the apparent equatorward propagation of auroral substorm absorption events at low auroral latitudes
Authors: Ziauddin Syed , Abdu M. A.
Published: April 2011

Auroral substorm absorption events observed at two stations. Val d'Or, P.Q. and Ottawa, Ont., located on the lower latitude side of the auroral zone (around L = 4) show a consistent tendency for an apparent equatorward propagation of the events. The observed velocities of propagation do not show any local time dependence or other trends expected from a pure gradient B drift of substorm electrons from the midnight precipitation region to the day side. Though a limited number of events are analysed the results indicate the possible influence of strong electric fields on the drift velocities of the substorm electrons.
The density dependence of the Hanle effect in the resonance line of atomic magnesium
Authors: Kelly F. M. , Mathur M. S.
Published: April 2011

The Hanle width and hence the lifetime of the first excited 1P1 level of neutral magnesium have been measured over a wide range of densities. The natural lifetime of the 3s3p1P1 level is 2.00 ns. The depolarization cross section for collisions with the ground level neutral atom has been measured and [Formula: see text].
A 2972 Å up–down photometer for rocket studies of the aurora
Authors: Sivjee G. G. , McEwen D. J.
Published: April 2011

A compact photometer for monitoring the total brightness of the O I (3P – 1S) line at 2972 Å along a rocket trajectory, is described. Its use as an aid in separating spatial and temporal changes from altitude variations in auroral intensity is illustrated by an application of the information gathered from such a photometer to the simultaneously measured 5577 Å brightness. An altitude profile of the 5577 Å volume emission rate has been derived showing the lower edge of emission at 112 km and a vertical half-width of 4 km. A 2972/5577 brightness ratio of 0.05–0.08 was measured.
Raman scattering from impurities in nonmetals. I. Phonon effects
Authors: Chow H. C.
Published: April 2011

The influence on the impurity Raman spectrum owing to the variation of phonon frequencies with the occupancy of the impurity state is studied. For a Hamiltonian which simulates the situation of change in phonon frequencies, the Raman spectrum function, which yields information about the total scattered intensity per unit time per unit solid angle as well as the line shape, is expressed exactly as a triple integral. It is shown that when the impurity state interacts predominantly with a single phonon mode, a set of lines appear which are displaced at equal frequency interval from the (zero-phonon) Raman lines. Under the condition when they are unresolvable owing to instrumental width or when the impurity is coupled with the continuum phonon spectrum, these additional contributions asymmetrically broaden the zero-phonon Raman lines.
π+–p elastic scattering at 47.9 MeV
Authors: Auld E. G. , Axen D. , Beveridge J. , Duesdieker C. , Felawka L. , Ingram C. H. Q. , Johnson R. R. , Jones G. , LePatourel D. , Orth R. , Salomon M. , Westlund W. , Robertson L. P.
Published: April 2011

The differential cross section for π+–p elastic scattering at 47.9 MeV has been measured in the angular range from 30 to 170° in the laboratory system. The three phase shifts extracted from these data, δS3 = −4.7 ± 0.5°, δP31 = −0.53 ± 0.14°, and δP33 = 5.1 ± 0.3°, are consistent with phase shifts obtained at other energies.
The spin–Peierls transition of the X–Y model in a magnetic field
Authors: Tannous C. , Caillé A.
Published: April 2011

The dependence of the spin–Peierls transition temperature Tc on an external magnetic field H is investigated for the quasi-one-dimensional (1D) X–Y model. Physical quantities such as the specific heat and susceptibility are evaluated for the spin–Peierls transition in a magnetic field in view of direct comparison with future experiments.
Two-dimensional hydrodynamic simulations of a laser heated gas target plasma
Authors: Milroy R. D. , Capjack C. E. , McMullin J. N. , James C. R.
Published: April 2011

The CO2 laser heating and the resulting hydrodynamic expansion of a gas target plasma is examined by means of a two-dimensional computer simulation. These plasmas are found to exhibit characteristic scale lengths of the order of 1 mm. Electron temperatures vary up to about 200 eV whereas ion temperatures vary up to about 50 eV. Electron density is found to vary all the way from above critical in a shock front to well below critical in the laser heated region behind the shock.
Analysis of the 118.6 μm laser magnetic resonance spectra of PH, X3Σ− and a1Δ
Authors: Davies P. B. , Russell D. K. , Smith D. R. , Thrush B. A.
Published: April 2011

Measurement and analysis of the 118.6 μm far infrared laser magnetic resonance spectra of the PH radical in its X3Σ− and a1Δ states are reported. The following rotational and fine structure parameters have been determined: X3Σ−: B0 = 8.412018 (27) cm−1, λ0 = 2.2067 (15) cm−1, γ0 = −0.076476 (48) cm−1; a1Δ: B0 = 8.4392925 (46) cm−1. The derived hyperfine constants are: [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text]; a1Δ: aH = 28 (15) MHz, aP = 768 (37) MHz. Within experimental error the hyperfine parameters yield identical values of [Formula: see text] for both electronic states.
Monte Carlo test of the T-expansion approach to range and depth calculations at low energies
Authors: Latta B. M.
Published: April 2011

The transport equations for the range and depth are derived in the approximation of equal spacing between collisions. The T-expansion solutions of these equations are compared with results from Monte Carlo simulations in the reduced energy interval from ε = 3.16 × 10−4 to ε = 10−1 for four projectile–target pairs. In the critical region of equal projectile and target masses, the T-expansion solutions for the mean depth were found to converge more rapidly than the mean-range solutions as higher order terms were retained. The greatest errors observed in the first approximation to the mean depth and mean range were, respectively, 21% for Bi on Ge and 59% for Au on Au. In addition, for the case of a heavy projectile on a light target, the standard method of extracting stopping cross sections (S) from experimental range data was investigated. This method, which is based upon the equation for the first approximation to the range, led to an overestimation of S of up to 49% when the method was applied to the Monte Carlo results for Bi on Ge.
Elastic and inelastic scattering of 40 MeV polarized protons from 90Zr and 92Zr
Authors: Swiniarski R. de , Pham Dinh-Lien , Bagieu G. , Geramb H. V.
Published: April 2011

Analyzing powers and cross sections have been measured for elastic and inelastic scattering of 40 MeV polarized protons from 90Zr and 92Zr. The analysis has been carried out in the DWBA within the framework of the macroscopic and microscopic models. Furthermore, the coupled-channels calculations using the vibrational model and the full Thomas form for the spin–orbit potential give a very good description for both the cross sections and the analyzing powers of the iow-lying2+, 3−, 5−, and 4+ states in 92Zr and the 2+ and 3− in 90Zr. The cross section and analyzing power for the first 2+ state in these nuclei were compared with previous results at 30 and 20.3 MeV, and from this comparison a certain energy dependence of the relative strength of the spin–orbit deformation to the central deformation could be observed. Microscopic model calculations with tensor and spin–orbit components included in the projectile–target real interaction and with an exact treatment of knock-on' exchange have been performed for the 2+ states in these nuclei. An attempt has also been made in order to include the imaginary component in the N–N interaction. For these calculations, rather good agreement was obtained especially for the 2+ state in 92Zr but poor agreement for 90Zr. Finally, valence plus core polarization calculations have also been done and showed a very good agreement between theory and experiment for those 2+ transitions.
Relation between the primary proton energy and the produced pion energy in p–p inelastic interactions in terms of the Landau parameter
Authors: Roychoudhury R. K. , Bhattacharyya D. P.
Published: April 2011

Taking (y, pT) as fundamental coordinate and a formula for the structure function for the reaction p + p → π± + X obtained from the hydrodynamical model, the relation between the incident primary proton energy Ep and the secondary pion energy Eπ in the laboratory frame has been estimated. The relation follows the form[Formula: see text]where L is the Landau parameter, B = 6.25, and mp = 0.938 GeV is the proton mass.
The distortion moment spectrum of GeH4: the microwave Q branch
Authors: Kagann R. H. , Ozier I. , McRae G. A. , Gerry M. C. L.
Published: April 2011

Ten pure rotational Q-branch transitions of the distortion moment spectrum of GeH4 have been measured between 9 and 23 GHz. They were observed in a conventional Stark modulated spectrometer modified to have a sensitivity of 1 × 10−11 cm−1. No Ge isotope splitting was observed in the spectrum. The spectrum was analysed in terms of a single set of six tensor centrifugal distortion constants DT, H4T, H6T, L4T, L6T, and L8T. The results were found to predict accurately transitions previously reported from infrared–microwave double resonance spectroscopy, and a complete analysis using both sets of data was carried out. The results are (in hertz): DT = 67 775.54 ± 0.86; H4T = −5.3827 ± 0.0055; H6T = 2.9693 ± 0.0019; L4T = (3.996 ± 0.088) × 10−4; L6T = −(4.122 ± 0.050) × 10−4; L8T = −(8.01 ± 0.14) × 10−4. The errors here are the standard deviations obtained from the least-squares analysis; estimates of the absolute errors are also given. For possible application in other high resolution studies, the constants have been used to calculate all tensor splittings for J ≤ 20.
Exchanged momentum between moving atoms and a surface wave: theory and experiment
Authors: Huard Serge
Published: April 2011

Momentum transfer during the resonant interaction between moving atoms and surface waves is calculated using a semi-classical method. Results show a greater Doppler shift than the one obtained in similar analysis with a plane homogeneous wave interacting with moving atoms. In order to measure such a small frequency shift, an atomic clock technique is used (accuracy: 10−10). An appropriate choice of surface wave frequency is the centimetre wavelength. The ΔF = 1, Δm = 0 transition in 87Rb is used and detected by the well-known optical pumping method.Experimental results are obtained for two different Rb atom speeds and compared with theoretical values.
Empirical formulas for 14 MeV neutron induced (n,α) cross sections
Authors: Pai H. L. , Andrews D. G.
Published: April 2011

The empirical formulas for 14 MeV neutron induced (n,α) cross sections have been examined. Both of the formulas suggested by Levkovskii and by Gardner and Yu can be explained primarily by the statistical model, based upon the constant temperature level density formula. The effect of neglecting the spin term in this simplified model appears to be insignificant.
Absorption spectrum of the H2S molecule in the vacuum ultraviolet region
Authors: Masuko Harunobu , Morioka Yumio , Nakamura Masatoshi , Ishiguro Eiji , Sasanuma Michio
Published: April 2011

The optical absorption spectrum of the H2S molecule in the region from 2050 to 1150 Å has been studied by a photographic method, using the radiation from a 1.3-GeV electron synchrotron as a background source. Numerous bands including those due to dipole forbidden transitions are observed in the spectrum. Five types of Rydberg series are assigned to electronic transitions from the outermost 2b1 orbital to the d-like orbitals, three types to the p-like orbitals, and one type to the s-like orbital. The quantum defects of these transitions and a series limit of 84 417 ± 8 cm−1 (10.466 ± 0.001 eV) were determined using the extended Rydberg series. The first member of the A Rydberg series splits into four bands, which is discussed with jj coupling scheme. The upper state of the 2000-Å (6.20-eV) broad band is assigned to the (2b1)−1 (6a1/4sa1) 1B1 state which is predominantly of valence orbital character. Transitions to vibrationally excited state were also investigated and the limit to which the (100) vibrationally excited Rydberg series converges was determined to be 86 882 ± 20 cm−1 (10.772 ± 0.003 eV). The results obtained in this experiment are compared with theoretical calculations.
The electronic absorption spectrum of NHD
Authors: Ramsay D. A. , Wayne F.D.
Published: April 2011

Rotational assignments are given for about 350 lines in the (0,9,0)–(0,0,0), (0,10,0)–(0,0,0), and (0,11,0)–(0,0,0) bands in the electronic absorption spectrum of NHD. The Σ and Δ sub-bands have been identified for the bands with ν2′ odd and the Π sub-band for the band with ν2′ even.Ground state rotational and spin–rotational constants have been determined. The principal constants in reciprocal centimetres are: A = 20.1162(32), B = 8.1114(16), C = 5.6681(16), εaa = −0.2324(51),εbb = −0.0373ε, εcc = −0.0019ε, where the error limits are 1σ. Term values are tabulated for both the ground and excited state levels.Several 'axis-switching' branches have been identified in agreement with the predictions of Hougen and Watson.
High resolution rotation–vibration Raman spectra of benzene. III. The spectrum of C6D6
Authors: Hollinger A. B. , Welsh H. L. , Jammu K. S.
Published: April 2011

The Raman spectrum of benzene-d6 vapour was excited in a multiple reflection cell by an Ar+ laser and was photographed with a spectral slit width of ~0.15 cm−1. Extensive structure (164 maxima) was observed for the ν2 (C—C stretching) fundamental but only the S branch (39 maxima) of the ν1 (C—D stretching) band was well-resolved. These totally symmetric bands were analysed and molecular constants determined from a least-squares fit. Three doubly degenerate bands were observed; ν15 and ν16 were unresolved, and in ν17 only 19 lines could be measured. Consequently, no detailed analyses were possible but the values of some molecular constants were estimated.
A study of the 34S(α,γ)38Ar reaction
Authors: Sinha K. N. , Hwang A. G. , Mak H.-B. , Evans H. C.
Published: April 2011

The reaction 34S(α,γ)38Ar has been investigated in the energy range Eα = 2.0–3.5 MeV. Eighteen resonance levels were found, nine of which have not been previously reported; six of the new levels have J > 1. The excitation energy, Jπ, decay scheme, mixing ratio, and transition strength for decays from the resonances were deduced.
Calcul d'inerties collectives hydrodynamiques en fission nucléaire
Authors: Fontaine Marie , Amiot Pierre
Published: April 2011

We develop a hydrodynamical method to calculate the inertia matrix elements for highly deformed nuclei. The nuclear velocity field is incompressible but is not limited to the adiabatic case. The formulation is also more general than Werner–Wheeler's. It is shown that off-diagonal terms play an important role in the determination of the normal modes of fission by diagonalization of the matrix.
Off-shell resonances in coupled channel problems
Authors: Pantis G.
Published: April 2011

The coupled channel theory of nuclear reactions is extended off the energy shell so that the T-matrix can be constructed to include both the direct reaction contribution and the contribution from the off-shell background scattering. This has been shown to be important for (d,p) stripping reactions to unbound states. Three soluble two-channel models with square well, δ-function, and separable potentials, are presented and the resonance and bound state behaviour is discussed in some numerical detail. The importance of the off-shell background term is also studied.
On the constraints that duality imposes on the broken SU(6)w structure of the baryonic resonance photocouplings
Authors: Avilez C. , Cocho G.
Published: April 2011

The absence of exotics and the natural parity exchange dominance in the t-channel, in high energy meson photoproduction of nucleons impose, via duality, restrictions on the baryonic resonance photocouplings. In a broken SU(6)w parametrization these constraints allow different couplings for the [Formula: see text] and [Formula: see text] baryonic resonances and impose relations between the transitions to the 70 and 56SU(6)W representations. It is shown that the low energy baryonic resonance photocouplings are in good agreement with these high energy constraints.
Spectroscopic investigation of plasma turbulence
Authors: Al-Shiraida Y. S. , Hirose A. , Skarsgard H. M.
Published: April 2011

Optical studies of plasma fluctuations have been carried out in a toroidal, high-voltage discharge—the Plasma Betatron experiment at the University of Saskatchewan. Following the formation of the helium plasma, of density 1019–1020 m−3, by rf preionization and a preheating field, the electric field (≤ 8 kV/m) of the main discharge is applied parallel to the steady toroidal magnetic field of 0.3 T. Forbidden lines and satellites observed near the He I 21P–41D (4922 Å) and 23P–43D (4471 Å) lines show that low [Formula: see text] and high (ω ~ ωpe) frequency fluctuations are present at early times (t < 2 μs). The rms field strengths are comparable, at [Formula: see text]. An analysis is given of the possible role of these fluctuations in the rapid thermal transport previously observed from the current skin layer to the interior of the plasma. Direct energy transport by propagating electron plasma or ion acoustic waves is shown to be insignificant. However, the low frequency field strength is sufficient to allow for an explanation in terms of enhanced thermal diffusion due to lower hybrid waves.
The lattice dynamics of crystalline carbon disulphide
Authors: Grout P. J. , Leech J. W.
Published: April 2011

The lattice dynamics of crystalline CS2 at 0 K is discussed within the rigid molecule, harmonic, and pair potential approximations. By including atom–atom point electric dipole interactions in a potential tailoring method introduced by Leech and Pawley equilibrium conditions are satisfied and excellent agreement is obtained between observed and calculated zero wave vector phonon frequencies and lattice energy. There is disagreement with other estimates of the magnitudes of some of the atom–atom interactions. Phonon dispersion curves for three high symmetry directions are presented.
Open orbits in ReO3
Authors: Razavi F. S. , Datars W. R.
Published: April 2011

Open orbits in the metal oxide ReO3 were studied by the induced torque method at a temperature of 1.4 K with magnetic fields up to 5.5 T.[Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] open orbits were detected. The results show that the third-band Fermi surface of ReO3 is connected along [Formula: see text] directions as predicted by Mattheiss' augmented-plane-wave band structure calculation. The angular magnetic field range for observation of open orbits and the relative number of primary and secondary open orbits are given.
A study of the sphericity in inelastic hadronic reactions at 24 GeV/c with the help of 'principal axis' variables
Authors: Ghosh D. C. , Naha S. C. , Roy T.
Published: April 2011

In this paper the sphericity of hadronic reactions is investigated with the help of the 'principal axis' variable method, using our data from p–nucleon interactions at 24 GeV/c. The multiplicity dependence and possible significance of the results are discussed.
Search for long-lived states of the heavier rare gas negative ions
Authors: Hird B. , Ali S. P.
Published: April 2011

A pure quartet state is expected in the energy spectrum of all the heavier rare gas negative ions which is metastable for autoionization to the ground state of the neutral atom. If this state occurs below the energy of the parent np5(2P3/2)(n + 1)s[3/2] state then it may be possible to produce accelerated beams of the heavier rare gas negative ions as is now done using the (1s2s2p)4P state of He−. A search was made for the negative ions Ne−, Ar−, Kr−, and Xe− following double electron capture in a krypton target at energies near 50 and 100 keV in the energy range where the He+ double charge exchange cross section is at its maximum. No definite evidence was found for any of these heavier rare gas negative ions, and they must all therefore have lifetimes less than 10−6 s.
Effects of coherently excited Zeeman transitions on a hydrogen maser hyperfine transition
Authors: Savard J.-Y. , Busca G. , Rovea S. , Desaintfuscien M. , Petit P.
Published: April 2011

The effects of transitions excited within the F = 1 multiplet of the ground state hydrogen atoms while radiating on the ΔmF = 0 transition are analyzed theoretically. The results are valid for low transition rates and unrestricted maser power. The predictions are: (a) an important modification of the well-known spin-exchange frequency shift of a hydrogen maser, due to the imaginary part of the spin-exchange cross section, (b) a frequency shift proportional to the asymmetry parameter between the 2-Zeeman frequencies in the upper multiplet F = 1, and (c) a frequency shift proportional to the polarization of the atoms in the storage bulb.Also shown is a displacement of the zero crossing of the maser detuning vs. the low frequency coherent transition frequency with respect to the dip of the maser absorption. This effect is visible for a maser tuned by spin-exchange and operated at a relatively high magnetic field and nonuniform Zeeman populations.An experimental verification of the theory is presented. A new method for tuning the hydrogen maser is suggested, and a proposal is made to measure the collisional frequency shift proportional to the average duration of hydrogen atom spin-exchange collisions.
Optical transitions in the modulated reflectivity spectrum of ion-implanted GaAs
Authors: Giorgianni U. , Grasso V. , Mondio G. , Perillo P. , Saitta G.
Published: April 2011

The wavelength modulated reflectivity spectrum of ion-implanted GaAs in the photon energy range 1.5–7.0 eV is reported. The specimens were obtained by 400 keV Te implantation at room temperature. Strong differences were found with respect to the optical behaviour of flash-evaporated films and crystalline samples. The Penn theory for materials with tetrahedral short-range order was applied and the absorption coefficient of ion-implanted GaAs is also reported.
Collective phenomena in the one-dimensional three-particle model of high-energy potential scattering
Authors: Inozemtsev V. I.
Published: April 2011

Within the framework of an exactly solvable model of three particles interacting through zero-range forces it is shown that the high-energy scattering with high momentum transfer is due to collective phenomena. The spectrum of particles scattered through 180° is compared with the results of impulse approximation.
Electroluminescence from single crystal Cu2O diodes
Authors: Chee K. T. , Keowsim T. , Weichman F. L.
Published: April 2011

We have measured the infrared electroluminescence in different types of single crystal Cu2O–Cu diodes under forward bias at various temperatures. Diodes which showed double-injection current-voltage characteristics in previous studies showed transient electroluminescence response at low currents and dc response at higher currents. On the other hand, diodes that showed the characteristics of single injection in previous studies showed transient electroluminescence response only. We have related the present studies on electroluminescence with the previous findings. Furthermore the present studies also revealed some information on the injection process. We have also discussed the differences and similarities between electroluminescence and photoluminescence of Cu2O.
The blΣ+–X3Σ− band system of the PBr molecule
Authors: Colin R.
Published: April 2011

Six bands of the b1Σ+–X3Σ− transition of the PBr molecule have been observed in a microwave discharge of PBr3 + He. High resolution spectra have allowed the rotational analysis of the 0–0 and 1–1 bands. The principal molecular constants obtained are:X3Σ−: P79Br; ωe = 458.35 cm−1, Be = 0.16067 cm−1; P81Br; ωe = 457.78 cm−1, Be = 0.15958 cm−1; re = 2.1714 Å.B1Σ+: P79Br; ωe = 485.47 cm−1, Be = 0.16509 cm−1; P81Br; ωe = 483.84 cm−1, Be = 0.16399 cm−1; re = 2.1421 Å and Te = 11779.75 cm−1.
Coulomb excitation of low-energy levels in 45Sc
Authors: Patil V. U. , Kulkarni R. G.
Published: April 2011

Low-lying negative parity levels in 45Sc were Coulomb excited with 2.5 to 3.5 MeV protons and 4 to 5 MeV 4He ions to test the weak coupling core-excitation model. A Ge(Li) detector was used to measure the gamma-ray yields. The 543, 976, 1408, and 1662 keV levels in 45Sc were Coulomb excited for the first time. Gamma-ray angular distributions were measured at 3.0 MeV proton energy in deducing multipole mixing ratios and spin values. Energy level measurements (in units of kiloelectronvolts) and spin values obtained are as follows: 976, 5/2, 7/2 and 1408, 7/2. The E2 and M1 reduced transition probabilities were determined for the six states. The 376, 720, 1237, 1408, and 1662 keV levels have properties consistent with the interpretation of coupling a 1f7/2 proton to the first 2+ core state.
Application of finite difference methods to the inverse problem of wave propagation
Authors: Hron M. , Razavy M.
Published: April 2011

Two methods of determining the wave velocity in an inhomogeneous medium from the reflection coefficient are presented. The medium, which is assumed to be bounded on one side by a perfectly reflecting surface, is divided into homogeneous layers with equal travel times, and the wave equation is solved within each layer. By matching the solutions at the boundaries, a nonlinear difference equation for the ratio of the amplitudes of the in- to the out-going waves in adjacent layers is obtained. This equation which relates the variable wave velocity to the phase shift can be solved by continued fraction expansion for the direct or the inverse problem. An alternative method consists of transforming the one-dimensional wave equation into a similar equation by replacing the spatial coordinate by the travel time coordinate. Converting this transformed equation into a linear difference equation with variable coefficient, the direct problem is reduced to that of calculating two phase shifts, one a discrete form of the JWKB phase and the other the phase shift obtained from the Schrödinger equation. This latter phase can be found conveniently from a discrete form of the variable phase equation. The inverse problem in this case becomes the same as the determination of a "potential" from the phase shift in quantum scattering theory.
On the relations between nonrelativistic binding energies of a neutral atom and isoelectronic ions
Authors: Lai C. B.
Published: April 2011

A relation between the nonrelativistic binding energies of a neutral atom and isoelectonic ions is proposed to account for the binding energies of isoelectronic ions, by using the first three energy coefficients in the 1/Z expansion.
Electron – hydrogen atom collision in the presence of a circularly polarized laser field
Authors: Barros H. G. P. Lins de , Brandi H. S.
Published: April 2011

Electron–hydrogen collision in the presence of a circularly polarized laser field is studied within a formalism based in an appropriate space-translations transformation and the Green's function formalism. The Born–Oppenheimer approximation for the scattering amplitude is obtained and the dependence of the differential and total excitation cross section on the electromagnetic field polarization is studied.
The p-phonon processes in impurity optical spectra
Authors: Barrie Robert
Published: April 2011

The expression is derived for p-phonon processes accompanying an optically-induced electronic change of state of an electron bound to an impurity site in a semiconductor or insulator. It is shown that a previously-derived line-shape function gives the correct expressions for these processes. The bound electron interacts with the phonons via terms linear and quadratic in the phonon variables.
Re-examination of high pressure electron transport properties of GaAs
Authors: Lee H. J. , Woolley J. C.
Published: April 2011

Previous data by Pitt and Lees on the pressure variation of the electrical conductivity σ and Hall coefficient RH of n-type GaAs samples have been reanalyzed using a three band (Γ, L, X) model. Calculations of σ and RH have been made using the method of Fletcher and Butcher and the resulting values fitted to the experimental data using the pressure coefficients of the band energy differences, the deformation potential EDX of the X band, and the coupling coefficient DLX between L and X bands as adjustable parameters and taking all other scattering parameters from a previous analysis of the temperature variation of σ and RH. The results give values of EDX and DLX of 12.5 eV and 1.1 × 1011 eV/m, respectively, and stress the importance of interband scattering in determining electron mobility values.
Exact and Glauber amplitudes in multi-channel scattering
Authors: Dijk W. van , Razavy M.
Published: April 2011

A model for one-dimensional many-channel scattering of a particle from a composite system is considered. It is assumed that the target cannot break up. Using Bellman's method of invariant embedding, a system of non-linear first-order differential equations with one-point boundary conditions is obtained for the transmission and reflection coefficients. These equations have stable numerical solutions. An alternative invariant embedding with the approximation of no reflection at any stage of the scattering process yields the Glauber approximation for the transmission coefficients. These formulations are used to compare the exact and the Glauber amplitudes for a projectile scattering from a bound two-particle system. It is found that unlike the inelastic Glauber amplitudes, the elastic Glauber amplitudes are very good approximations to the exact results.
Measurement and analysis of the ν2 and ν4 infrared bands of CD4
Authors: Kreiner W. A. , Robiette A. G.
Published: April 2011

The infrared spectrum of CD4 has been recorded between 942 and 1201 cm−1, encompassing the ν2 and ν4 bands. The data have been analysed taking account of the Bζ24 Coriolis coupling term linking the upper states of the two bands. Six hundred seventy-five assigned transitions, reaching a maximum upper state J value of 20 in each band, have been fitted with a standard deviation of 0.013 cm−1 and new values of the molecular constants are reported.
Off-shell T-matrix in nuclear reactions
Authors: Pantis G. , Sprung D. W. L.
Published: April 2011

We propose an off-shell extension of the T-matrix in nuclear reaction theory, by utilizing the R-matrix formalism. The method is illustrated by an analysis of two different two-channel models.
(n,n′γ) studies of 114,116Cd
Authors: Newton T. M. , Davidson J. M. , Dawson W. K. , Green P. W. , Hooper H. R. , McDonald W. J. , Neilson G. C. , Sheppard D. M.
Published: April 2011

Energy levels below 2.2 MeV excitation in 114,116Cd have been investigated using the (n, n′γ) reaction. Gamma-ray angular distributions were measured, and energy levels, spins, and gamma-ray multipole mixing ratios were deduced. Levels and their spins have been confirmed at 1134 (0), 1210 (2), 1283 (4), 1365 (2), 1733 (4), and 1843 (2) keV for 14Cd and at 1213 (2), 1220 (4), and 1381 (0) keV for 116Cd. New spin assignments have been made for the levels at 1861 (3) and 2049 (3) keV for 114Cd and at 1644 (2,3) and 1917 (3) keV for 116Cd. The states at 1959 keV in 114Cd and 1923 keV in 116Cd are shown to be consistent with assignments of 3.
On electromagnetic plane wave scattering by a prolate spheroid
Authors: Sinha B. P. , MacPhie R. H.
Published: April 2011

The exact solution in terms of vector prolate spheroidal wave functions for scattering of a plane wave of arbitrary polarization and angle of incidence by a conducting prolate spheroid, obtained in a previous paper by the authors, is utilized to obtain the expansion in the far zone of the scattered field in terms of the much simpler spherical vector wave functions. This extends the range of such formulations, heretofore available only for the low frequency domain, to the resonance region and beyond.
l-resonance perturbations in overtone and combination vibrational systems of C3ν molecules
Authors: Lauro C. di , Lattanzi F.
Published: April 2011

The problem of the l-resonance between different vibrational components of combinations and overtones in symmetric tops is considered and is examined in detail for C3ν molecules. Matrix elements are given for the general case, including vibrational states with multiple excitation of degenerate normal modes. The conditions for the splitting of rotational sublevels are also determined.As an example, the theory is applied to the ν2 + ν6, ν5 + ν6 perturbed infrared system of methyl bromide, and the computed band contour is shown to be in agreement with the experiment.
Helm model interpretation of 16O form factors: application to pion photoproduction and muon capture
Authors: Graves R. D. , Lamers B. A. , Nagl Anton , Überall H. , Devanathan V. , Subramanian P. R.
Published: April 2011

The available experimental data for the form factors of the T = 1 levels in 16O, obtained from electron scattering at low (Darmstadt), medium (Tohoku), and high momentum transfer (Stanford), are interpreted by the generalized Helm model. This phenomenological model reduces the form factor description of each level to the listing of a few physical parameters, i.e., the radius and smearing width of the transition densities of charge (current) and magnetization, and their corresponding strength constants. Its parameters having been determined by the form factor fits, the model may then be used to predict the results of other medium energy processes; this is done here for the photoproduction of charged pions and for muon capture in16O.
Photovoltaic effect and Schottky barriers in the Au–In1−xGaxSb system
Authors: Keeler W. J. , Roth A. P. , Fortin E.
Published: April 2011

The temperature dependence of the photovoltaic effect between 6 and 300 K has been measured on the Au–In1−xGaxSb system. Analysis of the data gives the Schottky barrier heights across the alloy system. In the n-type region of the system (InSb rich) the barrier is found to be [Formula: see text] while in the p-type region (GaSb rich) it is [Formula: see text].
Résonateur ouvert en géométrie sphérique
Authors: Duret Gilles , Zepp Gérard , Wick Alain
Published: April 2011

Most of the approximate theories of the spherical open resonators are insufficient, except for the very large radius of curvature. It is often necessary to consider other cases. The theory we have developed is applicable for any curvature and aperture of the mirrors. This theory also allows study of multi-dielectric cavities. This method is accurately studied in detail in this paper.
The spin XY model. IV. Analysis of high temperature series expansions of some thermodynamic quantities in four dimensions
Authors: Rogiers J.
Published: April 2011

The series for the fluctuation of the order parameter and the fourth-order fluctuation of the order parameter of the S = [Formula: see text] XY model on four-dimensional lattices are analysed. Assuming a simple power law we find γ = 1.125 ± 0.010 for the simple hypercubic and γ = 1.113 ± 0.005 for the face-centred hypercubic. An alternative method of analysis which includes a logarithmic correction factor and assumes γ = 1 gives as power for the logarithmic correction p = 0.36 ± 0.05 for the simple hypercubic lattice.
Plasma current multiplication at high current levels
Authors: Shmayda W. T. , Stangeby P. C.
Published: April 2011

The plasma current multiplier, PCM, is a simple gas discharge device which has the capability of amplifying small cathode currents to large anode currents. Experimental results are presented for the current gain of a PCM operating on argon and covering a range of gas pressures and current levels. It is found that gain increases with pressure and decreases with current density. A theory is presented which explains the experimental observations. Gas rarefaction due to heating by the discharge electrons is found to play a dominant role in high current PCM operation.
Vector mesonic decays of 1/2+ baryons in charm changing mode
Authors: Kanwar Satish , Verma Ramesh C. , Khanna M. P.
Published: April 2011

Charm changing parity violating (pv) weak decays of 1/2+ baryons are studied in the channel (1/2+ → 1/2+ + 1−). We compare the decay amplitude relations in Left [Formula: see text] Left and Left [Formula: see text] Right current–current interaction pictures in SU(4). We further extend these considerations to SU(8), thereby introducing quark spin. We notice that the B(3) → B(6) + V(8) mode, forbidden in the Glashow–Illopoulos–Maiani (GIM) scheme, arises through a right-handed current (RHC) interaction, whereas B(3) → B(8) + V(3*) vanish independently of the nature of the weak current.
Generalized power spectra and the Stokes vector representations of ultralow frequency micropulsation states
Authors: Olson J. V. , Samson J. C.
Published: April 2011

We present a description of a formalism for the detection and analysis of polarization states of arbitrary three-dimensional waveforms based upon the extensions of state vector concepts used in the descriptions of photons in optics and quantum mechanics. The formulation is based upon the interpretation of the spectral matrix which represents the waveform as a density matrix. Once this connection is established the power representing a general information state may be estimated. Expansion of the spectral matrix in a basis set of trace-orthogonal matrices leads to the Stokes vector representation of the signal waveform. This compact representation provides very direct routes to the estimation of various important signal parameters such as polarization, ellipticity, etc. The techniques are applied to a set of ULF waveforms which are scanned for the presence of magnetospheric resonances. The location of the resonant L shell with respect to the magnetometer station is established verifying the power and utility of the analysis techniques.
A stability analysis of immiscible viscous displacement in a homogeneous porous medium
Authors: Spanos T. J. T.
Published: April 2011

The stability of viscous displacement in a porous medium is considered in terms of the stability of fluid wave propagation in the medium. The concept of a critical wavelength is used to describe the criteria for the onset of fingering and the transition from the range for which Darcy's equation applies to the conditions under which the Brinkman equation must be used.
Optical spectra of ZrS3
Authors: Perluzzo G. , Jandl S. , Girard P. E.
Published: April 2011

We report the thermomodulated reflectivity and transmission at 300 and 80 K of the trichalcogenide compound ZrS3. An indirect gap around 2 eV has been found and the ground state of the exciton at the lowest allowed direct transition measured at 2.5 eV. More or less resolved structures were identified at 3.18, 3.95, 4.28, and 4.59 eV in the thermorefiectivity spectrum.
Optical model analysis of nucleon scattering from isobars A = 92
Authors: Kulkarni V. , Rapaport J.
Published: April 2011

An optical model analysis of nucleon scattering from isobars, 92Zr and 92Mo, is presented. Simultaneous analysis of either neutron or proton elastic scattering data on both isobars yields results for the isovector part of the optical potential consistent with previous results.
Properties of 11.05 MeV state in 14N
Authors: Rangacharyulu C. , St-Pierre C.
Published: April 2011

The gamma decay of Ep = 3.77 MeV resonance in 13C(p,γ)14N has been measured. From the measured excitation functions, the natural width of the resonance was deduced to be 1.2 ± 0.4 keV. The resonance is found to strongly populate the 3.945 MeV level, in addition to the gs transition. Gamma angular distribution measurements determined the resonance spin as 3+. The reduced proton width is found to be 0.5% of the single particle unit. The transition strengths are measured to be B(E2) = 0.45 ± 0.07 and 3.0 ± 0.8 Wu for transitions to ground state and the level at 3.945 MeV, respectively.
Specific heat of ordered equiatomic InMg, CuPt, and CuAu I below 30 K
Authors: Martin Douglas L.
Published: April 2011

The results of specific heat measurements on ordered In −51.67 at.% Mg are presented. A superconducting transition was seen at about 0.95 K. In the normal state, the lattice specific heat varies in the usual way with temperature, i.e., the Debye temperature initially decreases with increasing temperature. This behavior was also seen in ordered equiatomic CuPt but in ordered equiatomic CuAu I the Debye temperature first goes through a maximum before decreasing to the usual minimum. The structure of all three alloys consists of alternating layers of different mass and it was initially supposed that the CuAu I result was a two-dimensional effect. However, the more recent and normal results on InMg and CuPt make this improbable and it appears that the CuAu I result is related to the behavior of pure gold which is itself anomalous.
A self-consistent set of neutron separation energies
Authors: Islam M. A. , Kennett T. J. , Kerr S. A. , Prestwich W. V.
Published: April 2011

The (n,γ) reaction has been used to establish a self-consistent set of neutron separation energies. Through examination of composite targets with a common component 13 elements have been studied, yielding some 20 Q values. The average precision was estimated to be 0.08 keV with the separation energy differences having a precision of 0.14 keV. In most cases agreement between the present and the accepted values was within the quoted error of the latter. The isotopes reported and (the separation energy in kiloelectronvolts) are 10Be (6812.1), 25Mg (7330.5), 26Mg (11 092.9), 28Al (7725.2), 29Si (8473.7), 30Si (10 609.7), 33S (8641.6), 36Cl (8579.8), 41Ca (8362.8), 45Ca (7414.9), 48Ti (11 626.5), 49Ti (8142.3), 50Ti (10 939.7), 51Cr (9261.8), 53Cr (7939.6), 54Cr (9719.0), 56Mn (7270.6), 55Fe (9298.0), 57Fe (7646.2), and 58Fe (10 044.7).
Paramétrisation canonique de la bande d'yrast
Authors: Amiot Pierre
Published: April 2011

We underline the requirement for a canonical formalism in the identification of the backbending in the nuclear yrast band. To obviate the absence of such formalism we propose a VMI type of empirical parametrisation which dynamically unifies the yrast band and allows a clearly canonical identification of the backbending.
The ram effect for a conducting cylinder in a drifting plasma
Authors: Brooks W. S. C. , Koehler J. A.
Published: April 2011

The flux differences between the front and rear face of an isolated conducting cylinder in a drifting plasma are calculated. It is shown that the ion temperature affects the fluxes weakly and that, for most cases, applicable to sounding rockets or spacecraft, the flux difference is linearly related to drift velocity.
Parity-mixing below 30 MeV excitation energy in the 4He system
Authors: Bevelacqua J. J.
Published: April 2011

Parity-mixing matrix elements for ΔT = 0 and ΔT = 1 transitions are calculated for selected transitions below 30 MeV excitation energy in the 4He system. The effective potential of Box, McKellar, Pick, and Lassey is utilized in the calculations. The results are based on detailed 4He wave functions which are calculated in a [Formula: see text] model space. The calculated parity-mixing matrix elements are in qualitative agreement with those predicted on the basis of a least-squares fit to 2 ≤ A ≤ 181 data by Desplanques and Missimer. The ΔT = 0 matrix element is calculated between the (0+,0)20.1 MeV level and the (0−,0)21.1 MeV level, while the ΔT = 1 matrix element is evaluated between the (1+,0) 25.5 MeV level and the (1−,1) 27.4 MeV state. The ΔT = 0 and ΔT = 1 calculations lead to parity-mixing matrix elements of −0.014 and +0.049 eV, respectively. These matrix elements correspond to parity-mixed components which are 10−8 smaller than the dominant parity component of an energy level. The parity-non-conserving (PNC) transitions lead to circular polarizations of 1.2 × 10−7 for the (1+,0) 25.5 MeV level and −2.2 × 10−8 for the (1−,1) 27.4 MeV level. The inclusion of a neutral current enhancement factor of about 10 increases the ΔT = 1 parity-mixing matrix element by about a factor of two.
Molecular dynamics by neutron scattering in pure hydrogen and a mixture of hydrogen and argon gases
Authors: McPherson R. , Egelstaff P. A.
Published: April 2011

The inelastic scattering of 2.4 Å neutrons by two states of pure hydrogen and two states of a mixture of hydrogen and argon (at a similar density) have been studied. From these data relaxation times for the velocity auto-correlation function of each state are obtained and are compared to the predictions of a simple hard sphere kinetic theory. It is found that, although the relaxation time depends on the momentum transfer, for pure hydrogen the prediction is in general agreement with experiment. For the mixture the prediction is about 2.5 times larger than the measured values, which is attributed to the reduction in the 'persistence' of the velocity after a collision.
An example of a double hypernucleus
Authors: Mandal P. , Saha M.
Published: April 2011

In a sample of approximately 300 hypernuclear decays found in 1.8 GeV/c K− interactions in nuclear emulsion, one triple centered event was observed. The event has been identified as a double hyperfragment, the most likely interpretation of the event being a [Formula: see text] and/or a [Formula: see text] and decaying successively by the following modes,[Formula: see text]The values of BΛΛ and ΔBΛΛ obtained are 20.6 ± 1.7 and 3.4 ± 1.7 MeV, respectively, for the first interpretation and 19.7 ± 1.8 and 1.7 ± 1.8 MeV for the second interpretation.
An examination of Doppler shift attenuation factors and lifetimes for excited nuclear states in 59Cu and 63Cu
Authors: Cooke B. E. , Leslie J. R. , McLatchie W. , Skensved P.
Published: April 2011

Excited states in 59Cu and 63Cu have been studied with radiative proton capture. Doppler shift attenuation factors have been measured for γ-rays depopulating these states, with ion recoil speeds of approximately 0.1% of the speed of light. Measurements of resonance strengths reported here, together with existing data from other techniques, have been used to deduce lifetimes for the same states. For five cases where the DSA factors and the lifetimes have been determined independently, consistency with DSAM theory is optimized when the standard energy loss value is multiplied by a factor of 0.94 ± 0.11.
Parameters of thermoelectric power of liquid metals of groups IIB, IIIB, and IV
Authors: Sahay B. B. , Srivastava P. L.
Published: April 2011

A pseudo-potential which is parabolic in r in the inner core region has been used to compute thermopower parameters of Zn, Cd, Hg, Al, In, Tl, and Pb directly through the derivatives of their electrical resistivities with respect to energy at the Fermi energy.The model presents improved results and numerical values are close to the experimental measurements.
Soliton solutions of coupled nonlinear field equations
Authors: Lai C. S.
Published: April 2011

A scheme for finding some exact soliton solutions of coupled nonlinear field equations is proposed. By assuming that one of the scalar fields can be expressed in terms of the other scalar field in quadratic forms, soliton solutions can be easily derived from the consistency relations between the coupled field equations. The present method of finding soliton solutions is simpler and more fruitful than that of Rajaraman which uses an integro-differential constraint equation.