bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of the static electron gas screening function on the lattice dynamics of sodium
Authors: Geldart D. J. W. , Taylor Roger , Varshni Y. P.
Published: April 2011

The static electron gas screening function calculated by Geldart and Taylor has been used in conjunction with the theory of Vosko, Taylor, and Keech to calculate the phonon dispersion curves, the effective calorimetric and X-ray Debye temperatures, and moments of the phonon frequency distribution function of sodium. The results which compare very favorably with those obtained using other screening functions give good agreement with experiment, indicating that the new screening function is reasonably adequate for calculations in sodium.
Nonlinearity of charge flow in conductor systems
Authors: Kak Avinash C.
Published: April 2011

Conductor systems do possess a small degree of nonlinearity on account of the nonlinear nature of all charge flow equations. Harmonic generation due to these nonlinearities has been investigated in the case of an infinitely long cylindrical wire made of copper carrying a travelling wave of current. It has been shown that the magnitude of the second harmonic current, caused by nonlinearity by the fields required to maintain a given travelling wave current distribution of fundamental frequency f on the wire, is frequency dependent, being proportional to f3/2. The magnitude of the second harmonic current is also directly proportional to the square of the magnitude of the fundamental frequency component. At a frequency of 10 000 MHz, the ratio of second harmonic component of current to the square of the magnitude of the fundamental frequency component of current is of the order 10−13 A−1. This order of magnitude though extremely small for most practical purposes can lead to spurious signal generation if the wire is surrounded by unstable plasma, since unstable plasma under certain conditions is capable of amplification. The order of magnitude of the second harmonic also suggests how far one should go in the direction of generating spectrally pure waves if they are to be propagated over conductor systems. The problem has been solved by analyzing the conductor system at the microscopic level making use of charge–kinetic equations.
On the uniqueness of the Møller energy–momentum complex
Authors: Halpern Leopold , Miketinac Milivoj J.
Published: April 2011

Møller's tetrad energy–momentum complex is made unique by introducing a suitable Yang–Mills field. The field equations are given and solved approximately for the spherically symmetric case. The simplest couplings to the K0 meson field are analyzed and it is shown that they cannot be used to resolve the CP violation.
The thermal conductivity and electrical resistivity of gold from 80 to 340 K
Authors: Cook J. G. , Meer M. P. van der
Published: April 2011

The electrical resistivity and thermal conductivity of a sample of pure gold has been measured from 80 to 340 K, using apparatus designed for the simultaneous measurement of these properties. The results are compared with those of previous investigators, and with the Bloch–Wilson theory.
Magnetic moment of iron–nickel invar alloys from 4 to 80 K
Authors: Cochrane R. W. , Graham G. M.
Published: April 2011

The magnetic moment of several ferromagnetic face-centered-cubic iron–nickel alloys in the invar region have been investigated at low temperatures, as a function of both the magnetic field and the temperature. A vibrating-sample magnetometer was used, for which relative changes in the moment of 3 parts in 105 could be resolved. Such resolution has permitted a detailed analysis of the temperature dependence of ΔM/M, the relative deviation of the magnetic moment from its value at 0 K, in terms of a contribution arising from spin-wave excitations, varying as T3/2, and one from single-particle excitations, varying as T2, both of these at constant volume, together with a term describing the effect of volume dilation on the moment. The fits to the data for H = 10 kOe yield, for 34 at. % Ni:[Formula: see text]and for 40 at. %Ni:[Formula: see text]
Excitation of singly-ionized barium ions by electron impact
Authors: Davis J. , Morin S.
Published: April 2011

We present cross-section calculations for excitation of singly-ionized barium ions by electron impact over the energy range from 3 to 100 eV. The cross sections were evaluated using Burgess' semiclassical method. Finally, our predictions are compared with two other current techniques and some recent experimental measurements. The agreement was found to be good.
Lyman–α excitation and resonant charge exchange in slow H+–H(1s) collisions
Authors: Knudson Stephen K. , Thorson Walter R.
Published: April 2011

The dominant processes in slow collisions (E < 0.5 keV) of protons and 1s hydrogen atoms are direct elastic scattering, resonant charge exchange, and direct and exchange excitations of H(2p). Differential cross sections have been calculated for all these events by both quantal and classical methods, and characteristics of the resulting Lyman–α (Ly–α) radiation determined.Significant differences from earlier calculations are found for excitation probability, polarization of Ly–α, and the interference oscillations in the charge exchange probability. The phase of the latter is a sensitive function of the interactions causing inelastic scattering. The source of discrepancy with earlier results is the use of the impact parameter approximation (straight-line trajectories); over the range of significant excitation probability, classical path methods using true trajectories give accurate inelastic parameters. Comparison of quantal and classical calculations shows that accurate results for all properties discussed can be obtained by combining classical path calculations of inelastic parameters with semi-classical phase shifts for pure elastic scattering.If polarizations calculated here are used to reinterpret earlier observations of Ly–α emission from 300 eV collisions, the resulting experimental cross sections are not inconsistent with the basic theoretical prediction of equal direct and exchange excitation probabilities.
Ionic conductivity of potassium iodide crystals
Authors: Chandra Suresh , Rolfe John
Published: April 2011

The electrical conductivity of pure KI, KI + SrI2, and KI + K2CO3 single crystals was measured as a function of temperature. A method for calculating ionic transport parameters from these results was developed, assuming that the conductivity was due entirely to the motion of positive and negative ion vacancies, and including the effect of association and Coulomb interaction between oppositely charged defects. It was shown that the Coulomb interaction had an appreciable effect on the high-temperature intrinsic conductivity, and the extrinsic conductivity of heavily doped crystals. Calculation of transport parameters from intrinsic-conductivity measurements alone gave erroneous results. From the agreement (within experimental error) between the experimental and calculated results, it was concluded that the only defects taking part in the conduction process were Schottky defects. The following parameters were calculated: Schottky-defect formation enthalpy hs = 2.21 eV, entropy ss = 0.765 × 10−3 eV/deg; positive ion vacancy migration enthalpy Δh1 = 0.63 eV, entropy Δs1 = 0.136 × 10−3 eV/deg; negative ion vacancy migration enthalpy Δh2 = 1.29 eV, entropy Δs2 = 0.805 × 10−3 eV/deg; association of divalent cations and positive ion vacancies enthalpy χ = 0.54 eV, entropy η = 0.190 × 10−3 eV/deg.
Determination of the solar-flare cosmic-ray rigidity spectrum using the worldwide neutron monitor network
Authors: Palmeira R. A. R. , Bukata R. P. , Gronstal P. T.
Published: April 2011

The determination of the rigidity spectrum of solar-flare-produced cosmic rays is examined. A method based on the ratio of relative enhancements observed at two stations sufficiently separated in latitude is discussed, and graphs are presented showing the expected ratio of enhancements as a function of the spectral exponent of the flare-produced cosmic rays for 6 pairs of stations. This method, which assumes that the cosmic-ray particles arrive at the earth isotropically, is then applied to the 28 January 1967 event during which this condition of isotropy is shown to exist. An extension of this method to the case of anisotropic arrival of solar cosmic-ray particles using the concept of variational coefficient is outlined.
A study of evaporated superconducting weak-link junctions
Authors: Iwanyshyn O. , Leslie J. D. , Smith H. J. T.
Published: April 2011

The current–voltage characteristics and voltage oscillations of evaporated, superconducting weak-link junctions have been investigated. The zero-voltage current variation with temperature is shown to be similar to that for a Josephson junction. A simple theory based on part of the superconductor switching normal enables us to explain the voltage snapback. A model based on thermal instabilities due to bubbles in the liquid helium in contact with the junction has been used to explain the voltage oscillations.
High-resolution gamma-ray study of 185Wm
Authors: Gujrathi S. C. , D'auria J. M.
Published: April 2011

The decay of 185Wm has been investigated using a high-resolution Ge(Li) X-ray spectrometer and a Ge(Li)–NaI(Tl) coincidence system. The energies and relative intensities (given in parentheses) of the observed gamma rays associated with the decay of the 185Wm (T1,2 = 1.68 min) are: 23.54 (3.3), 42.29 (1.1), 65.857 (100), 93.30 (0.5), 94.59 (2.2), 107.850 (6.8), 122.05 (1.5), 131.554 (84.0), 164.334 (11), 173.675(61.5),and 187.879(15.4) keV. The energy of the isomeric level has been deduced to be 197.41 keV and decays to the ground state through levels at 187.88, 173.68, 93.29, 65.86, and 23.54 keV. In addition, it was deduced experimentally from measured internal-conversion coefficients that the multipolarity of the 131.55 keV transition is E3 while the 65.86 keV transition is an M1 + E2 mixture with a 30 ± 7.5% M1 component.
Vibrational Raman spectra of liquid and solid ethylene
Authors: Blumenfeld S. M. , Reddy S. Paddi , Welsh H. L.
Published: April 2011

The Raman spectra of liquid and solid C2H4 have been examined at a reciprocal linear dispersion of 8 cm−1/mm. The liquid spectrum presents some evidence of short-range order in the liquid near the freezing point. The gerade fundamentals and low-frequency librational modes have been observed in the Raman spectrum of the solid. Analysis of the observed splitting in terms of H-atom repulsion indicates that the intermolecular force constant is 950 dyn/cm, and the crystal structure is P21/n1. The origin of other observed structures is uncertain.
Nuclear magnetic resonance and magnetic structure of antiferromagnetic Mn2P2O7
Authors: Choh Sung Ho , Stager C. V.
Published: April 2011

The nuclear magnetic resonance of 31P in antiferromagnetic Mn2P2O7 has been investigated at constant r.f. frequencies with the external field smaller than the spin-flop field. Resonance measurements were made in a single crystal sample at liquid helium temperatures. Experimental data, including the angular dependence, the external field dependence, and the temperature dependence of the resonances, are satisfactorily explained by the spin Hamiltonian formalism for NMR in antiferromagnets, proposed by the authors. NMR results confirm the spin direction obtained from susceptibility measurements, and establish the magnetic space group as C2c2.
Time-dependent gap equation for pure superconductors
Authors: Leung M. C.
Published: April 2011

The time-dependent gap equation is derived by including real scattering processes which are the essential causes of the fluctuations of the order parameter.
Properties of the 2.645, 2.693, 3.001, and 3.162 MeV levels in 35Cl
Authors: Taras P. , Matas J.
Published: April 2011

Angular distributions and linear polarizations of the gamma rays emitted in the 35Cl(p, p′γ)35Cl reaction have been measured. Four resonances were investigated at proton energies of 4.24, 4.82, 5.08, and 5.11 MeV. The spin and parity of the levels at 2.645, 2.693, and 3.001 MeV in 35Cl have been deduced to be 7/2+, 3/2+, and 5/2+, respectively, while the spin and parity of the 3.162 MeV level have been confirmed to be 7/2−. The multipolarity mixing ratios of the decay of these four levels to the ground state have been found to be δ(M3/E2) = 0, δ(E2/M1) = +0.26 ± 0.03, δ(E2/M1) = +0.07 ± 0.02, and δ(E3/M2) = −0.25 ± 0.04, respectively. In addition, the branching ratios for the decay of these four levels have been determined.
Rotational Raman spectrum of nitric oxide
Authors: Shotton K. C. , Jones W. Jeremy
Published: April 2011

The pure rotational Raman spectrum of nitric oxide has been recorded for the first time under high resolution. Analysis of the S-branch transitions yields values of 1.69614 cm−1 and 5.46 × 10−6 cm−1 for the rotational constants B0 and D0, respectively. A series of R-branch lines is observed and is shown to arise from transitions between levels in the 2Π3/2 substate. Some weaker R-branch lines arising from the 2Π1/2 state are also observed. A very weak feature approximately 120 cm−1 from the exciting line is interpreted as the 2Π3/2–2Π1/2 transition.
Delay time and phase of the initial state
Authors: Gien Tran Trong
Published: April 2011

The study presented in this paper is intended to show how to calculate the average delay time of a scattering within the framework of the delay time operator Q in order to prove that the average delay time is independent from the phase of the initial state. This conclusion differs from Ohmura's assertion in a recent paper that in the three-dimensional scattering, the average delay time depends on the phase change of the initial state. Our result saves the hope that the delay time of a collision can be known in terms of the S matrix alone. The reason for the difference between our result and Ohmura's is also discussed. We also investigate the commutation of the Q and S matrices and search for the interesting consequences of this commutation.
Collision frequency of electrons in the F region
Authors: Setty C. S. G. K. , Jain A. R. , Vyawahare M. K.
Published: April 2011

The collision frequency of electrons in the F region of the ionosphere has been measured at Delhi (geographical latitude 28°38′ N, geographical longitude 77°13′ E) using a method similar to that suggested by Appleton. The amplitude and group path of short radio waves vertically incident on the F region of the ionosphere have been measured simultaneously at a suitable frequency (for both the ordinary and extraordinary wave modes) in early morning and late evening hours, corresponding to times of appearance and disappearance of the echo, respectively. Simultaneous changes in amplitude and group path are related to deduce the collision frequency. Some selected records taken near the time of sunrise have been analyzed and the values of collision frequency are found to be (4.2 ± 0.5) × 103 and (3.5 ± 0.5) × 103 s−1 for the ordinary and extraordinary waves, respectively, in the true-height range of 270–310 km.
Mutual coupling effects in linear antenna arrays
Authors: VanKoughnett A. L.
Published: April 2011

The effects of mutual coupling among the array elements on the pattern and impedance characteristics of linear antenna arrays are examined. Based upon the assumption that the mutual impedance of two array elements depends only upon the separation of the elements, exact expressions are derived for the properties of infinite and semi-infinite arrays. Integral equations which describe finite arrays are derived and solved for special forms of the mutual impedance behavior and for large arrays.
Intensity anomaly in the (d,pγ) reaction
Authors: Bartholomew G. A. , Bergqvist I. , Earle E. D. , Ferguson A. J.
Published: April 2011

The spectra of gamma rays detected in coincidence with protons from the (d,pγ) reaction in elements [Formula: see text] and [Formula: see text] have been measured in gross structure with a NaI detector. The region of excitation energies covered in the product nuclei was from 0.8 MeV to about the neutron separation energy, typically 7 MeV. The gamma-ray anomalous bump at about 5.5 MeV was found from regions near the separation energy with an intensity comparable to that previously observed in (n,γ) reactions. By gating techniques the decay of many contiguous intervals of excitation energy, populated in the reaction, was studied. From the results, a strength function for gamma rays between 0.8 and 7 MeV approximately was extracted for Au, where the bump is prominent, and for Ta where the bump is essentially absent. In the particular case of 206Pb(d,pγ)207Pb, the gamma-ray spectra are interpreted in terms of the decay of known single particle states. An interpretation of the intensity anomaly in terms of doorway states is discussed.
Determination of spin–rotation interaction constants in fluorinated methane molecules by means of nuclear spin relaxation measurements
Authors: Dong Ronald Y. , Bloom Myer
Published: April 2011

The proton and fluorine spin relaxation time T1 has been measured in CH4, CF4, CHF3, and CH3F gases at low densities. By measuring the dependence of T1 on density near the characteristic T1 minimum, new information has been obtained on the spin–rotation interaction coupling constants in CF4, CHF3, and CH3F. The CH4 system was used to test the validity of this method since the spin–rotation coupling constants are accurately known for CH4. The correlation function for the spin–rotation interaction was found to be exponential within experimental error for all of the molecules studied. In the analysis of the experimental data, the effects of the dipolar interactions and of nuclear spin symmetry considerations were completely neglected. The validity of these approximations is discussed in the Appendix.
Radiowave absorption at an auroral latitude
Authors: Gregory J. B. , Manson A. H. , Rees D. T.
Published: April 2011

Radiowave absorption at 2.2 MHz has been measured by the A1 method (vertical incidence, pulse), during noon periods from November 1967 – October 1968 at Saskatoon (52° N, 106° W, 61.5° invariant latitude). Monthly mean values are not strongly determined by direct solar control. Maxima of absorption are found in February, and in September–October, during which periods there is increased auroral activity. Correlation with magnetic activity on a daily basis is poor except during these months, and is good only when ΣKp is greater than 6 (6 h) during high absorption events. The "winter anomaly" of absorption, as evidenced in a log ρ, log (cos χ) plot, is present in modified form, when compared to mid-latitude seasonal variations. A regression equation shows that the response of absorption to changes in stratospheric temperatures over the Canadian prairies is less than to changes in Kp and is below the significance level of 10%. The coefficients of the temperature and Kp terms in the regression relation for eastern Canada (Ottawa, L = 3.6) are highly significant.
The magnetic susceptibility of CsTi(SO4)2∙12H2O
Authors: MacKinnon John A. , Bickerton James Leonard
Published: April 2011

The magnetic susceptibility of CsTi(SO4)2∙12H2O (CsTi alum) was measured with a Foner magnetometer in the temperature range 4.2 to 300 °K. Emphasis was placed on the liquid-helium to liquid-nitrogen temperature range, since complete measurements for this temperature region have not been reported previously.The experimental results were interpreted with an expression derived by Kamimura for the effective moment of Ti3+ ions as a function of temperature in a crystalline electric field of trigonal or tetragonal symmetry. A best fit to the experimental data was obtained with values of [Formula: see text] and λ = 25.2 ± 5.0 cm−1. These values indicate the presence of an excited energy state approximately 30 cm−1 above the ground state; in addition there is a substantial reduction in the spin–orbit coupling factor from the free-ion value.
Study of the 1459-keV level in 19F by the 19F(p,p′γ)19F reaction
Authors: Lam S. T. , Litherland A. E. , Simpson J. J.
Published: April 2011

The 1459-keV level of 19F was populated by the 19F(p,p′γ)19F reaction at a proton energy of 2.78 MeV. The E2/M1 mixing ratio for the 1459 → 110 keV transition was determined to be [Formula: see text] from a combination of the γ-ray angular distribution and linear polarization and the nuclear lifetime. The γ-ray angular distribution was measured with a coaxial Ge(Li) detector and the γ-ray linear polarization with a planar Ge(Li) detector. The corresponding E2 and M1 transition strengths for a lifetime of 0.084 ± 0.020 ps are found to be [Formula: see text] and 0.10 ± 0.03 W.u. respectively. They are in good agreement with the particle–hole calculations of Benson and Flowers. The branching ratios of the 1459-keV level agree well with those of Poletti et al. The γ-ray transitions from the 1459-keV level provide a good example for demonstrating the usefulness of a single crystal Ge(Li) polarimeter.
Random phase errors in arrays of line-source antennas
Authors: Dudley D. G.
Published: April 2011

An analysis of phase errors in arrays of line-source antennas containing random dissimilarities in wave-guide cross section is presented. The expectation of the Fraunhofer power response is derived. A transformation is found which, through use of the central limit theorem, allows derivation of the complete probability distribution of the electric field in the side-lobe region. For errors small enough, the field is given very nearly by the Rice distribution. The results are used to relate manufacturing tolerance to side-lobe deterioration.
A time-correlated study of the Z-pinch discharge in helium
Authors: Dimoff K. , Tam S. Y. K.
Published: April 2011

The development of a miniature "gradient probe" and the successful superposition of multiple photographic recordings have produced useful insight into the action of the Z-pinch discharge in helium.A correlation of luminosity and current fronts yields strong evidence for the occurrence of a nonionizing shock wave at high initial pressures in helium discharges. The relatively nonluminous shock front is followed by overlapping regions of He I and He II radiation within the collapsing current shell. At low filling pressures these two regions coincide and radiation is emitted from almost all the gas trapped within the current shell. In all cases the zone of maximum He II emission is observed to coincide with the position of maximum current density.Synchronization of the discharge current with time-resolved spectroscopic results indicates the presence of successive pinches. They are caused by the interaction of thermal and magnetic pressures after the first collapse of the discharge.
Absorption spectrum of the Mg2 molecule
Authors: Balfour W. J. , Douglas A. E.
Published: April 2011

The absorption spectrum of the Mg2 molecule, which occurs in a furnace containing Mg vapor, has been photographed with a high resolution spectrograph. The rotational structures of the bands have been analyzed and the rotational and vibrational constants of the two states determined. The bands are found to arise from a 1Σ–1Σ transition between a very lightly bonded ground state and a more stable excited state. The R.K.R. potential energy curve of the ground state, which has a dissociation energy of 399 cm−1, has been determined. The more important constants of the ground state are ωe = 51.12 cm−1, ωexe = 1.64 cm−1, re = 3.890 Å and those of the upper state are ωe = 190.61 cm−1, ωexe = 1.14 cm−1, re = 3.082 Å.
Plasma neutrino emission from stars and its astrophysical evidence
Authors: Chaudhuri Probhas Ray
Published: April 2011

The emission of neutrino pairs by a stellar plasma is calculated according to the photon–neutrino coupling theory and is compared with the result obtained on the basis of the current–current coupling theory of weak interactions. We have also discussed the effect of the plasma neutrino emission on the evolution of white dwarfs. It is observed that the small fraction of the observed white dwarfs with masses above [Formula: see text] can be interpreted when the plasma neutrino emission is considered from the point of view of the photon–neutrino coupling theory.
Fine structure in the photoneutron spectra from praseodymium-141 and lead
Authors: McNeill K. G. , Jury J. W. , Hewitt J. S.
Published: April 2011

Careful measurements of the energy spectrum of photoneutrons ejected from praseodymium and from natural lead show that there are peaks on top of the expected smooth spectrum. Comparison with the recent cross-section studies, which indicate structure on the giant dipole resonance for these nuclei, shows agreement between the energies of the peaks found in the present work and the energies En = E−Qi where E corresponds to a peak in the cross-section curve and Qi is the threshold for producing a given state in the daughter nucleus. Only ground state transitions (for Pr) or ground state and the first two excited state transitions (for Pb) need be invoked.
98 and 102 kG niobium–titanium superconducting magnets
Authors: Atherton David L.
Published: April 2011

This note reports a niobium–titanium compound superconducting magnet which generates 98 kG in a [Formula: see text] in. (2.858 cm) bore and 102 kG in a 1 cm bore with an additional niobium–titanium insert. Comments on the design and performance are included together with an introductory summary of the comparative properties of niobium–tin and niobium–titanium superconducting magnets.
Le spectre électronique de la molécule As2
Authors: Perdigon Pierre , D'Incan Jean
Published: April 2011

Excitation by a high-frequency electromagnetic field of a mixture of neon and arsenic vapor at 380 °C allowed us to observe the already known transitions of the As2 molecule and to find two new systems, c → X and e → X. A rotational analysis has been carried out for several bands of a → X, A → X, B → X, d → X, c → X, and d → c systems, and corresponding rotational constants have been determined. From the results of this analysis, the nature of different excited states has been specified and it was shown that they belong to Hund's case c: the c state is formed by 0u− and 1u components of a 3Σu+ state; the a state is the 0u+ component of a 3Σu− state and the d (1 g) state seems to be in correlation with a 3Πg state: A and B states are 1Σu+states. Assumptions have been made as to the electronic configurations to which these states are ascribed, and to the dissociation products.
Transitional nuclei. I. Decay of 150Pm to levels of 150Sm
Authors: Barrette J. , Barrette M. , Monaro S. , Santhanam S. , Markiza S.
Published: April 2011

The energies and relative intensities of the γ transitions following the 150Pm decay have been measured using high-resolution Ge(Li) detectors. A total of 140 γ rays was observed and 117 of these transitions could be traced to 34 levels in the 150Sm nucleus. A large amount of information on the structure of the 150Sm nucleus could be extracted by a direct comparison of measured spectra inside and outside a well-type Ge(Li) spectrometer. In such a way sum lines arising from two (or more) coincident y rays could be detected easily, thus giving the possibility of obtaining direct coincidence information on the 150Pm decay in spite of its short half-life (2.7 h) and high complexity. Spin and parity assignments for levels in 150Sm are tentatively given, by also taking advantage of previous experimental studies available on this nucleus.
d3/2 hole states in scandium isotopes
Authors: Johnstone I. P.
Published: April 2011

Hole states in scandium isotopes are investigated by coupling a d3/2 hole to low-lying states of the neighboring titanium isotopes. Titanium wave functions are obtained by angular momentum projection from 1f2p-shell Hartree–Fock intrinsic states, and diagonalizations are carried out using the Gillet and Sanderson particle–hole interaction. The binding energies of the 3/2 + states in 43Sc, 45Sc, and 47Sc are well reproduced, as is the spacing between higher-spin levels of the K = 3/2 bands, and the polarization of the titanium cores has approximately the magnitude needed to account for the long M2 lifetimes. The model fails to give any low-lying hole states in 44Sc, but a calculation of spectroscopic factors does account for the absence of observable l = 2 strength below 1.6 MeV in the 43Ca(3He,d)44Sc reaction.
Interférence et modulation spectrale
Authors: Delisle Claude , St-Arnaud Jean-Marie
Published: April 2011

It has been shown by Mandel that the spectral density shows a cosine modulation with relative amplitude 2(Ī1 Ī2)1/2γ12(0)/(Ī1 + Ī2) when the optical path difference is much longer than the coherence length in a quite general superposition experiment of two quasi-monochromatic, polarized, and partially coherent beams of light. It is shown here that this is equally true for path differences smaller or equal to the coherence length. This conclusion is reached by considering the properly defined visibility of the modulation of the spectral density. Both aspects of the modulation of the spectral density are considered: modulation as a function of path difference for a fixed frequency ν0 and modulation as a function of frequency for a fixed path difference cT0.
Debye temperature of 24 cubic elements from elastic constants
Authors: Wanner René
Published: April 2011

Approximation methods for calculating the Debye temperature are compared with an exact numerical integration by computer to complement a paper by Konti and Varshni. Except for the alkali metals the agreement is about 0.1%.
Unified approach to the representations of groups SU(2) and SU(1, 1)
Authors: Young Klang-Chuen
Published: April 2011

A unified approach to the representations of groups SU(2) and SU(1, 1) is made. The method is based on the observation that SU(2) and SU(1, 1) can be considered as special cases of a group G(a). The representation of G(a) is realized in the space of homogeneous generalized functions. The canonical bases of the unitary irreducible representations are constructed explicitly. The matrix elements for the finite transformation are found. Explicit expressions for the Wigner coefficients are also obtained.
Specific heat below 3 °K, melting point, and melting heat of rubidium and cesium
Authors: Martin Douglas L.
Published: April 2011

Specific heat measurements were made between 0.4 and 3.0 °K. For rubidium (nominal purity 99.9%, actual purity probably ~ 99.99%) the electronic specific heat coefficient γ is 624.6 ± 6.5 μcal/°K2 g atom and the low temperature limiting value of the Debye temperature (ΘOoc) is 56.5 ± 0.2 °K. For cesium (nominal purity 99.99%, actual purity probably ~ 99.97%) γ is 950 ± 20 μcal/°K2 g atom and ΘOoc is 40.5 ± 0.3 °K. These Debye temperatures are in fair agreement with ΘOoc1 values calculated from low temperature elastic constant measurements. Electron effective masses (calculated from γ) are 1.37 ± 0.01 for Rb and 1.80 ± 0.04 for Cs. Thermal effective masses for all the alkali metals are compared with recent theoretical results. Sample purities were checked by an independent spectrographic analysis and by making a thermal analysis in the melting region on the actual specific heat samples. These thermal analysis results led to a review of earlier work on the melting of these metals and the following revised values of melting point and latent heat of melting were obtained: Rb: 312.47 ± 0.02 °K, 524.3 ± 1.0 cal/g atom; Cs: 301.67 ± 0.13 °K, 501.0 ± 1.0 cal/g atom.
Improvement of magnetic probe measurements
Authors: Curzon F. L. , Pachner Jr. J. , Tam Y. K. S.
Published: April 2011

By considering the current flow around a probe guide of a circular cross section, it is shown that the perturbed magnetic field can be partially "corrected" with a three coil probe. The theory has been tested in a coaxial cylindrical geometry, an analogue of a Z-pinch discharge. The spatial resolution l of the three coil probe is roughly one half of the probe guide radius, a. For current distributions which vary slowly with distance (scale length, λ) it is shown that the fractional error in the magnetic field is ~ 0.2(l/λ)2. For a single coil probe the error is at least four times as large.
Generalized perturbation theory for quantum oscillators
Authors: Webber J. C. , Paul R.
Published: April 2011

The time dependence of the quantum statistical density operator for oscillator systems (open or closed) is formulated within a generalized time-dependent perturbation theory. The new and more convergent perturbation series is also applicable to any boson system in nonequilibrium.
Duality and crossing symmetry of the narrow resonance model
Authors: Nakazawa K.
Published: April 2011

In the narrow resonance approximation, conditions of duality and crossing symmetry are derived using the finite energy sum rule for an amplitude which is completely determined as a function of two complex variables by its meromorphic part in one of these variables. As an example, the one term Veneziano amplitude is discussed.
A 3Σ–3Π transition of the SiO molecule
Authors: Nagaraj S. , Verma R. D.
Published: April 2011

The spectrum in the region 4200–4300 Å, attributed to the SiO molecule, has been excited strongly in a r.f. discharge through a mixture of argon and a trace of SiCl4 vapor flowing through a quartz tube. The spectrum consists of a single sequence Δν = 0. The 0–0 and 1–1 bands have been photographed at high dispersion. A rotational analysis of these bands shows that they involve a 3Σ–3II transition and not a 1Σ–3Π transition as reported earlier. The following rotational constants were determined:[Formula: see text]
WKB approximation in application to acoustic–gravity waves
Authors: Einaudi F. , Hines C. O.
Published: April 2011

The WKB approximation often provides a useful tool for the study of wave propagation through varying media. The utility of this tool in the case of acoustic–gravity waves, propagating through regions of varying background temperature, has been somewhat questionable because of an ambiguity in the assignment of an appropriate expression for the vertical wavenumber. The ambiguity is examined here, and shown to be inconsequential except in circumstances such that the WKB approximation is itself inapplicable; a unique choice of expression for the vertical wavenumber is recommended on the basis of simplicity and. utility. Conclusions reached in a number of recent papers are reexamined in the light of the insight that has been gained.
Retention coefficients and thermal release profiles of ion-injected argon from silicates and iron
Authors: Lord III Harry C.
Published: April 2011

Thermal release profiles and retention coefficients of injected argon ions were investigated as functions of substrate composition and prior ion-irradiation history. Samples of forsterite, enstatite, oligoclase, obsidian, and cold-rolled steel were irradiated with various sequences of 1 keV H+, 4 keV He+, and 40 keV Ar+. The release temperature of the maximum argon concentration was found to be a function of incident Ar+ dose and pre-irradiation history but not substrate composition. The hydrogen or helium pre-irradiation converted the volume diffusion argon release to a low temperature defect diffusion release. An increase in the incident dose of Ar+ ions resulted in increasing the percentage of the argon released by defect diffusion, and also decreased the argon retention coefficient.
Electronic specific heat of aluminum-based alloys
Authors: Carbotte J. P. , Truant P. T. , Dynes R. C.
Published: April 2011

It has recently been found that in aluminum-based alloys, the change in the logarithm of the specific heat with the logarithm of the electron concentration is more than three times the value expected from free electron model considerations. This is not likely to be a result of band structure. We suggest that this experimental behavior is a direct consequence of the strong dependence of the electron–phonon mass renormalization of the specific heat on the electron concentration.
Sensibilisation des émulsions ionographiques à l'alcool polyvinylique
Authors: Tanaka Keiichi , Demers Joseph , Demers Pierre
Published: April 2011

Ionographic emulsions were prepared using polyvinyl alcohol (APV) in place of gelatine by slightly modifying the method of Fujii et al., and without employing ammonia. Chemical sensitization was tried for recording RX (collective effect) and α rays (traces and collective effect) on this emulsion. Diphenylamine is useless, eosin has a weak effect, sodium nitrite is fairly active. Sulfur (S) (Na2S2O3) is better than TEA (triethanolamine), which causes more fog. In the case of TEA, soaking the dry film works better than adding it prior to pouring. TEA soaking of films poured with S is still better. When APV and gelatine are compared there is a difference with respect to sensitivity and fog (gelatine is superior). However, silver bromide sensitization in these two colloids obeys similar laws. S and TEA are effective, the latter especially by soaking, and TEA adds to the effect of S (hypersensitization). The sensitivity threshold, determined from the dose of 60 kV RX that produces a density of 0.2 above fog level, is 5 R for the non-sensitized emulsion and decreases to 0.75 R after sensitization.
Remark on memory function approach and linear response theory
Authors: Cheung T. H. , Tong E. , Wang K. P.
Published: April 2011

It is generally understood (Kubo) that the linearized version of the memory function approach of Mori and Zwanzig is equivalent, through the application of the fluctuation–dissipation theorem, to the corresponding linear response theory of correlation function calculations developed in the work of Kadanoff and Martin. We give here a simple example of spin diffusion to show this explicitly, which reflects the general connection between these two approaches.
Temperature and pressure variation of the 35Cl nuclear quadrupole resonance frequency in K2IrCl6
Authors: Baker Gregory L. , Armstrong Robin L.
Published: April 2011

Experiments to study the temperature and pressure variations of the 35Cl nuclear quadrupole resonance (NQR) frequency in K2IrCl6 are described. The resonance frequency at atmospheric pressure is measured from 3.08 °K (the antiferromagnetic transition temperature) to 470 °K. Measurements of the pressure dependence of the resonance frequency for pressures to 5000 kg cm−2 have been carried out at five temperatures between 281 and 393 °K. A multiple-mode method is adapted to include the effect of the destruction of π bonding by the lattice vibrations and is then applied to the analysis of the temperature variation of the resonance frequency. The temperature dependence of the oscillation frequency of the rotary lattice mode is deduced. The behavior of the torsional oscillation frequency is nearly identical with that observed in K2PtCl6. An analysis of the combined results of the temperature and pressure studies in K2IrCl6 and similar results in K2PtCl6 suggest that volume effects as well as the destruction of π bonding may be important for the explanation of the experimental temperature dependence of the NQR frequency.
Rotational analysis of the red electronic emission system of titanium nitride
Authors: Dunn T. M. , Hanson Louise K. , Rubinson Kenneth A.
Published: April 2011

An electronic emission spectrum has been obtained from a carrier identified as the diatomic molecule TiN. The system, which occurs in the red, has been analyzed as 2Πr → (X)2Σ, and it appears to be the analogue of the orange–red systems of the isoelectronic molecules CaF and ScO.The lower (ground?) state has B0″ = 0.6211 cm−1 corresponding to r0″ = 1.583 Å, whereas the excited 2Πr state has B0′ = 0.6103 cm−1. The system has a well-defined homogeneous perturbation in the excited state, showing the presence of a second, unobserved, 2Π term.
Theoretical calculations of electronic Raman effects of the NO and O2 molecules
Authors: Lepard D. W.
Published: April 2011

This paper presents a method for calculating the relative intensities and Raman shifts of the rotational structure in electronic Raman spectra of diatomic molecules. The method is exact in the sense that the wave functions used for the calculations may belong to any intermediate case of Hund's coupling schemes. Using this method, theoretical calculations of the pure rotational and electronic Raman spectrum of NO, and the pure rotational Raman spectrum of O2, are presented. Although a calculated stick spectrum for NO was previously shown by Fast et al., the details of this calculation are given here for the first time.
Light-modulated reflectance in CdS
Authors: Stößel W. , Colbow K. , Dunn D.
Published: April 2011

Reflectance spectra of CdS modulated by a second, intense light beam, show detailed structure due to excitons. This structure results from screening induced by the free carriers generated by the intense light beam. By maximizing the effect we were able to obtain considerably better resolved spectra than previous photo- or electro-reflectance measurements had given. A good theoretical fit was possible with a choice of reasonable parameters.
Decay of 17.7 min 120Sbg and 5.8 day 120Sbm
Authors: Pan P. J. , Hetherington D. W. , McConnell D. B. , Taylor H. W.
Published: April 2011

The decay of 120Sbg and 120Sbm was studied with a 33 cm3 Ge(Li) detector and a multichannel analyzer. Through the use of coincidence techniques, excited states of 120Sn were established at 1171.0, 1874.2, 2159.2, 2193.8, 2282.9, and 2479.6 keV. The results are compared to existing decay schemes for 120Sbg,m and the theoretical predictions of contemporary nuclear models.
Electronic structure and the dynamic Jahn–Teller effect on R′ centers in alkali halides
Authors: Inoue M. , Sati R. , Wang S.
Published: April 2011

The low-lying states of R′ centers in LiF, KCl, and KBr have been calculated using the quasicontinuum model of F aggregate centers. It turns out that the ground state of the R′ center is of 3A2 symmetry rather than 1A1 or 1E symmetry, and that the first excited state of the R′ center to which the optical transition occurs from its ground state is an orbitally doubly degenerate state (3E). The absorption line shape for the transition 3A2 → 3E of the R′ center has also been discussed for these crystals. The reasons for the presence of common features in the R′ bands in LiF, KCl, and KBr are pointed out. A comparison of the calculated results with the experimental results shows that the R′ band is due to the transition from the ground state of the R′ center (F3− center) to its first excited state perturbed by the dynamic Jahn–Teller distortion.
Night airglow hydroxyl rotational temperatures
Authors: Harrison A. W. , Llewellyn E. J. , Nicholls D. C.
Published: April 2011

Rotational temperatures have been determined from observations of the OH emission in the night airglow. It is proposed that an apparent increase in the derived rotational temperature with the value of K′ may be explained in terms of a nonisothermal emitting region.
Induced galvanomagnetic effects in copper
Authors: Datars W. R.
Published: April 2011

The galvanomagnetic properties of copper were studied by observing the torque induced in single-crystal copper by a slowly rotating magnetic field at 1.4 °K. The induced torque varied linearly with the speed of magnet rotation and quadratically with magnetic field. There was large induced torque in high-purity samples from the open orbits in both one-dimensional and two-dimensional regions. In a sample with low ωcτ, there was also a background torque. The induced torque is described by Falicov's solution of the boundary value problem for a sample sphere with a resistivity tensor. The open-orbit torque in an uncompensated metal such as copper is approximately proportional to the transverse resistivity component ρ11. The anisotropy of the open-orbit torques for the (100) and (110) planes of copper is in agreement with that calculated for the magnetoresistance from the Fermi surface of copper. There is anisotropy in the background torque with minima in the region of symmetry directions and for a rotation in a (100) plane.
Electrodisintegration of lithium
Authors: Wong C. F. , Hutcheon R. M. , Shin Y. M. , Caplan H. S.
Published: April 2011

Energy spectra of charged particles produced by electron and bremsstrahlung bombardment of 6Li and 7Li were measured by means of a magnetic spectrometer and solid-state detectors. Assuming that all transitions leave the residual nucleus in the ground state, the photonuclear cross sections were obtained using both bremsstrahlung and E1 virtual photon spectra. Comparison of the present real and virtual photon results is made with those of previous experiments.
Dispersion de réfraction de l'argon, du krypton et du xénon sous les états solide et liquide
Authors: Marcoux Jules
Published: April 2011

Variations of the index of refraction, in the visible region, for three rare gases, argon, krypton, and xenon, in the liquid and solid states have been measured. The measured values are given in table and graph form. The value of n∞ for solid xenon is determined.
Mechanism of a CO–N2 laser. II. Study by electronic spectroscopy
Authors: Taïeb G. , Legay F.
Published: April 2011

The study of the CO–N2 laser described in a preceding paper is pursued here by electronic spectroscopy. It is shown that the emission intensity of the red and violet systems of the CN radical present in the laser tube is related to the infrared laser action. Investigation of this effect leads to the conclusion that, after its formation, CN is electronically excited by collision, with vibrationally excited nitrogen molecules. The effect on the laser and CN emissions of a small addition of gases such as O2, NO, and CO2 is studied and discussed. All the observed facts are interpreted by a theory based only on the presence of N(4S) atoms and vibrationally excited molecules N2(X1Σg+).
Electroreflectance spectra of some II–IV–As2 compounds
Authors: Kwan Clarence C. Y. , Woolley John C.
Published: April 2011

The room temperature reflectance spectra of the ternary compounds of CdSnAs2, CdGeAs2, ZnSnAs2, ZnGeAs2, and ZnSiAs2 have been determined in the energy range 1.5–6.0 eV by reflectance, electroreflectance, and thermoreflectance techniques. Similar measurements have been made on alloys of the systems In2(1−x)ZnxSnxAs2 and In2(1−x)CdxSnxAs2. These latter data have enabled the spectral peaks of the ternary compounds to be labelled and distinction made between the zincblende peaks and extra peaks due to the chalcopyrite structure. Possible band transitions producing the extra peaks are discussed.
Courbes de visibilité du spectre cannelé
Authors: St-Arnaud Jean-Marie , Delisle Claude
Published: April 2011

A Michelson interferometer is illuminated by a parallel beam of white light. The visibility of the channelled spectrum or spectral density modulation at the exit of the interferometer is measured as a function of the path difference between the two beams formed in the interferometer. The experimental results show that the contrast has not completely disappeared for a path difference much larger than that already reported in the literature.
Infrared absorption due to H− ions in sodium and potassium halides. I. Anharmonic side bands of the local mode
Authors: MacPherson R. W. , Timusk T.
Published: April 2011

New measurements and calculations of the side bands of the local-mode absorption of H− ions in the infrared are presented for the potassium and sodium halides. Some new features are observed and a shell model for the defect along with phonon data determined from neutron scattering experiments is used to satisfactorily explain the observed spectra.
Admittance of a thick antenna
Authors: Jacobsen J. , Hurd R. A.
Published: April 2011

An asymptotic solution is derived for the admittance of a linear antenna. The solution is valid for antenna half-lengths greater than about λ/6 and for radii up to at least λ/6. Some representative curves of admittance are presented.
Comments on a study of the 23Na nuclear quadrupole spin–lattice relaxation in sodium nitrate
Authors: Hughes D. G. , Reed K. , Snyder R. E.
Published: April 2011

The orientation dependence of the nuclear quadrupole spin–lattice relaxation probabilities W1 and W2 measured by Niemelä for 23Na in NaNO3 is reanalyzed. It is shown that experiment and theory are in much more satisfactory agreement than previously supposed.