bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron diffraction study of the validity of the Th6 space group for solid carbon dioxide
Authors: Curzon A. E.
Published: April 2011

Electron diffraction patterns obtained with 65 kV electrons (wavelength = 0.0466 Å) from polycrystalline carbon dioxide at about 77 °K are in reasonable agreement with the patterns to be expected from a lattice having the accepted Th6 symmetry of solid carbon dioxide. The calculated and observed intensities of the rings agree, provided the parameter u which measures the separation of adjacent carbon and oxygen atoms is taken to be larger than u = 0.1083 which was obtained from earlier X-ray work. Agreement between experiment and theory is obtained for u such that 0.1083 < u < 0.1250 but further work is required if u is to be determined precisely.Detailed consideration is given to those rings for which H = √17 and H = √18, where H = √(h2 + k2 + l2). In the present experiments the observed intensities of these rings agree with the calculated intensities but similar agreement was not found in earlier X-ray diffraction work.
Segregation of (134Cs)+ impurity during growth of polycrystalline ice
Authors: Kvajić G. , Brajović V.
Published: April 2011

The distribution of radioactive impurities in the liquid and solid phases was measured during the growth of ice under a condition of one dimensional heat flow. The concentration of impurities along the specimen was proportional to the intensity of gamma rays detected by an Nal (Tl) photomultiplier and single-channel analyzer. A large impurity accumulation took place ahead of the crystal growing vertically upwards and the thickness of this impurity cloud is of the order of a few mm corresponding to the hydrodynamic instability region, between 0 and 4 °C, of maximum water density. Freezing downward does not show a detectable peak due to the strong convection where the diffusion coefficient is about 2500 times larger than for the diffusion of impurity in the case of freezing upward. Accumulation of impurity is a strong function of the V rate of freezing and of the initial impurity concentration C0. Impurity entrapment in ice is given in terms of the partition coefficients, Kef and Ki, which depend on V and C0. A morphological substructure of the solid-liquid interface is presumably changed during freezing runs thus causing a complicated dependence of Kef, Ki, and the coefficients of the impurity cloud size on the V rate and concentration C0.
Level structures of 91Rb and 91Sr as populated in beta decay
Authors: Mason J. F. , Johns M. W.
Published: April 2011

The decay of 7.9 s 91Kr and its 58 s daughter 91Rb have been studied with Ge(Li) plastic and NaI(Tl) detectors, singly and in coincidence, to determine the properties of states in 91Kr, 91Rb, and 91Sr. The energies and intensities of 9 gamma rays following the decay of 91Kr have been measured, locating levels at excitations of 0.1086, 0.5068, 0.7218, and 1.6154 MeV in91Rb. β–γ coincidence measurements involving the 0.1086, 0.5068, and 0.6132 MeV transitions have established the 91Kr – 91Rb mass differences as 5.08 ± 0.10 MeV.The energies and intensities of 36 gamma rays following the decay of 91Rb have been measured, identifying levels in 91Sr at 0.0931, 0.4392, 1.0414, 1.2306, 1.9426, 2.0643, 2.344, 2.6574, 2.9257, 3.6932, 3.737, 3.752, 3.935, 4.0785, 4.252, 4.265, and 4.497 MeV. The lifetime of the 0.093 MeV state is 91 ± 3 ns. The states at 2.6574, 3.6932, 4.0785, and 4.265 have negative parity.
Numerical integration of certain differential equations encountered in atomic collision theory
Authors: Lebeda Charles F. , Thorson Walter R.
Published: April 2011

The problem of accurate numerical integration of the general "two-state" coupled first-order equations frequently encountered in atomic collision theory is discussed. In particular, it is shown that an asymptotic expansion of the exact solution, valid for times early in the collision where the coupling is still weak, can be obtained by a simple iterative procedure. This expansion can be used to significantly shorten the range of numerical integration, by providing reliable starting values at finite times t0 where the coupling is not negligible though still weak. It is further shown that spurious small oscillations in the numerical solutions, which are generated when the usual boundary conditions for t → −∞ are used to provide starting values at finite times t0, can be removed by using the expansion for starting values at t0, with resulting improvements by several orders of magnitude in speed and accuracy of the numerical integration. This improvement is illustrated for an example where the coupling interaction has an especially long range.
Magneto-acoustic instabilities in weakly ionized gases. The validity of the adiabatic approximation
Authors: Carter C.
Published: April 2011

Some theoretical treatments of magneto-acoustic instabilities in weakly ionized flowing gases have used the adiabatic approximation, which assumes that changes in pressure and density are related in the same way as in a nonionized gas. The validity of this approximation is examined, particularly for four typical gas conditions which might occur in a subsonic magnetohydrodynamic generator. It is shown that the approximation may cause errors in the calculation of growth or decay rates, but that it is usually reliable in discriminating between stability and instability.
Rotational analysis of the forbidden d3 Δi ← X1Σ+ absorption bands of carbon monoxide
Authors: Herzberg G. , Hugo T. J. , Tilford S. G. , Simmons J. D.
Published: April 2011

The forbidden d3Δi–X1Σ+ transition of CO has been observed in absorption at high resolution in the vacuum ultraviolet region. The intensity distribution in the rotational structure of the observed bands is in conformity with the assumption that the transition occurs on account of the interaction between the d3Δ state and a 1Π state, presumably the A1Π state. Thirteen bands of the d–X system have been analyzed yielding more extensive rotational data for the d3Δi state than were previously known. A discussion of the local perturbations in the d state by the A1Π and a3Π states is included.
Calculations of fission parameters based on a "molecular model" of fission
Authors: Thind K. S. , Tomlinson R. H.
Published: April 2011

A 'molecular model' of fission, in which a fragment separation of 4.0 fm defines the scission point, is proposed. Using the fragment separation distance as a free parameter, the sum of the coulomb and deformation energies for the scission configuration is minimized. This provides a method for calculating the kinetic energies of fragments both at the scission point and at infinite separation. The fragment deformation energies have also been calculated.
Infrared and Visible Emission Spectrum of the NO Molecule. The 2Δ–2Π Bands of the 3d–3p and 4d–3p Transitions between Rydberg Complexes
Authors: Ackermann F.
Published: April 2011

The two mutually related bands B′2Δ–C2Π (7,0) → N2Δ–C2Π (0,0) and N2Δ–C2Π (0,0) → B′2Δ–C2Π (7,0) are observed with high resolution between 6620 and 6520 Å in the emission spectrum of the NO molecule. They are the 2Δ–2Π part of the 4d–3p transitions between the two Rydberg states N2Δ(4dδ) and C2Π (3pπ) of the molecule. A rotational analysis is carried out for both bands, and the very close similarity of the structure of these bands with the structure of the corresponding 2Δ–2Π bands of the 3d–3p transitions, observed in the infrared, is demonstrated. The two upper levels in these nd–3p transitions represent examples of mixed states showing complete changeover with increasing rotation from the Rydberg type with no spin–orbit coupling (AR = 0.00 ± 0.05 cm−1) to an inverted valence type and vice versa. The behavior of the doublet splitting is studied with regard to this changeover. The lower levels of the Rydberg state C2Π also are mixtures with levels of a valence state. The mixing with B2Π (ν = 7) is comparatively small in the C2Π (ν = 0) level, but it strongly affects the energy levels with the lowest J values. The beginning of one of the two bands observed in the visible, therefore, forms the (7,7) band of the system B′2ΔB2Π. Constants of the states involved are determined.
Binding Energy of with Two-Channel Separable Potentials
Authors: Chong K. F. , Law J.
Published: April 2011

Using the two-channel separable potentials of Nogami and Satoh, which are fitted to the hyperon-nucleon scattering data, the Λ binding energy in [Formula: see text] has been calculated using the model of Law and Nguyen. We find that the binding energy is sensitive to the coupling to the Σ channel. The results indicate that it is possible to obtain agreement with the experimental binding energy of [Formula: see text].
Spectra of H2–Ar, H2–Kr, and H2–Xe Van der Waals Complexes in Pressure-Induced Infrared Absorption
Authors: Kudian A. K. , Welsh H. L.
Published: April 2011

Spectra of H2–Ar, H2–Kr, and H2–Xe Van der Waals complexes, accompanying the Q1(0), Q1(1), S1(0), and S1(1) transitions of the pressure-induced fundamental infrared absorption band of hydrogen, have been studied in gas mixtures at 93–180 °K with a path length of 13 m and total pressures of ~3 atm. The main features of the spectra correspond to rotational transitions in the ground vibrational state of the complex, i.e., resolved T and N lines (Δl = ± 3) and unresolved R and P lines (Δl = ± 1), where l is the rotational quantum number of the complex. The spectra are analyzed with eigenvalues derived from the wave-mechanical solution of the isotropic Lennard–Jones 12–6 potential with constants determined from the combination rules for mixed molecular species. Although there is good overall agreement, it is evident that finer details of the spectra will require the introduction of an anisotropic intermolecular potential for their explanation.
Impurity Modes in an Induced Moment System and Hydrogen-Bonded Ferroelectrics
Authors: Pink D. A.
Published: April 2011

Impurity modes arising from the presence of an isolated impurity in an induced moment system and in KH2PO4-type ferroelectrics have been investigated. These two systems can be characterized by a parameter Δ′ which is the ratio of the energy difference between the lowest ionic states (or the tunneling integral in KDP) to the exchange (or interaction) constant. In the absence of external fields it is found that (i) impurity modes can exist at the top or bottom (where they give rise to scattering at low temperatures) of the excitation band, (ii) localized modes can appear in the energy gap below the band, and (iii) no modes exist for Δ′ larger than some critical value (except for modes at the impurity). A magnetic (or electric, in the case of KDP) field can cause modes to appear or vanish and can move the modes in and out of the band, thus localizing a resonance.
Cosmic Ray Intensity Decrease of 23 September, 1966
Authors: Desai U. D.
Published: April 2011

Earlier studies have interpreted the Forbush decrease of 23 September 1966 in terms of two phases; an initial predecrease and a later worldwide decrease. This interpretation precluded the possibility of correlation with a concurrent magnetic storm and led to an explanation of the predecrease (Mathews et al. 1968) in terms of a shadow cast by a distant plasma cloud approaching from a direction 85° to the west of the sun–earth line.In the present study, particle and magnetic field data from satellite-borne detectors and ground-based neutron monitors clearly show the onset of the Forbush decrease coincident with the SSC magnetic storm. It is pointed out that the Forbush decrease arises from a corotating shock front approaching from the east of the sun–earth line and is not associated with any solar flare effect. Further, the increases observed by the various neutron monitors 9 h after the onset of the Forbush decrease are interpreted to be an enhancement of the diurnal anisotropy. An example of an increase in intensity in the IMP 3 detector arising from electron contributions is also pointed out.
On the Interaction of Low Energy Pions with Nuclei
Authors: Scherk Leonard
Published: April 2011

It is shown that the low energy [Formula: see text] pion–nucleus optical potential, which has previously been derived by other authors from a microscopic point of view, has a simple geometric structure which can be understood from the analogous problem of adding electric potentials in a dielectric medium. The optical properties of this potential are dominated by the presence of a short-range local repulsion, which is comparable to the energies of interest, and by a strong momentum dependence in the optical interaction. It is shown that, because momentum-dependent processes are strongly suppressed near the top of the resulting potential barrier and because the nuclear density enters the optical interaction in a transparent manner, such momentum-dependent processes as pion absorption provide an excellent tool for investigating the structure of the nuclear surface. Such processes should finally resolve current inconsistencies in the knowledge of the neutron distribution in the nuclear surface.
Microwave Spectrum, Dipole Moment, and Quadrupole Coupling Constants of Carbonyl Cyanide, CO(CN)2
Authors: Lees R. M.
Published: April 2011

The microwave spectrum of carbonyl cyanide, CO(CN)2, has been investigated between 8 and 40 GHz. The rotational constants are A = 6761.1933 MHz, B = 2924.6686 MHz, and C = 2037.9934 MHz. The inertial defect of 0.433 U-Å2 is consistent with a planar structure. Spectra have been observed for the first and second excited states of a low-frequency in-plane vibration, which is assigned to ν5, the symmetric A1 CCC or CCN bending mode. The vibration–rotation interaction constants are α5A = −13.396 MHz, α5B = −13.367 MHz, and α5C = −1.924 MHz. The dipole moment is μb = 0.704 ± 0.007 D. The 14N quadrupole coupling constants are χaa = −2.846 ± 0.024 MHz, χbb = 0.045 ± 0.016 MHz, and χcc = 2.801 ± 0.032 MHz. With values of 1.22 Å and 1.165 Å assumed for r(C=O) and r(C≡N) and a linear CCN chain, the moments of inertia Ia and Ib are reproduced by values of 1.45 Å and 115°19′ for r(C—C) and [Formula: see text] respectively.
Optical Phonon-Assisted Transitions in Deep Acceptor Impurities in Silicon
Authors: Bhatia K. L.
Published: April 2011

The coupling between the lattice and the impurity bound carrier for deep monovalent acceptors in silicon, such as gallium and indium, is found to be stronger than for the shallower boron impurity. This suggests the possible existence of optical phonon-assisted transitions associated with these deep impurities. Such transitions are observed in the absorption spectrum of indium-doped silicon. The phonon-assisted transitions are superimposed on the photoionization continuum transitions of the indium acceptors. Interference effects between the phonon-assisted transition and the transition to the continuum states modify the position and line shape of the transitions. Using the phonon dispersion curves for silicon, interpretation of the results is presented. An estimate of the strength of the electron–phonon coupling in indium-doped silicon is obtained.
Rayleigh–Brillouin Scattering in Compressed H2, D2, and HD
Authors: Hara E. H. , May A. D. , Knaap H. F. P.
Published: April 2011

The Rayleigh–Brillouin spectrum of light scattered from H2, D2, and HD has been measured at densities ranging from 1/2 to 104 amagat, all at room temperature. The apparatus consisted of a 20 mW He–Ne laser, a high pressure cell for 90° scattering, a pressure scanned Fabry–Perot interferometer, and photon counting electronics. A discrepancy is noted between the observed spectra and various theoretical spectra. It is suggested that the discrepancy arises from an omission in the theories of coupling between relaxation of the rotational states and thermal conduction.
Boson Representations of the Heisenberg Model
Authors: Dharmawardana M. W. C.
Published: April 2011

Maleev's transformation to boson operators is often used to recover Dyson's result for the excitation spectrum of a Heisenberg ferromagnet. However, we show that a simple use of the Holstein–Primakoff transformation is adequate to obtain the same excitation spectrum. We have used a Zubarev-type Green function approach in which no decoupling approximation is needed. However, an approximation for the polarization operator is used.
Investigation of Hydrodynamic Surface Waves with a Cylindrical Microwave Resonator. IV. Application of a Strong Electrostatic Field
Authors: Curzon F. L. , Ionides G. N.
Published: April 2011

The reduction of the oscillation frequency of surface waves caused by a static electric field normal to the surface has been investigated with a microwave resonator. The stationary deformation of the surface caused by the spatially non-uniform field has been used to verify that the detectable wave amplitude is of the order of 5 × 10−3 cm, which is much smaller than other scale lengths (> 1 cm) of the system. The results can therefore justifiably be compared with the predictions of the linearized equations of motion. The experimental results agree well with the theory, which takes into account the spatial non-uniformity of the electrostatic field.
Currents Induced on a Conducting Strip
Authors: Shafai Lotfollah
Published: April 2011

An integral equation for the singular currents on a conducting strip illuminated normally by a plane electromagnetic wave polarized parallel to the strip is obtained and the singularities of the currents are treated by using a conformal transformation. The integral equation is then solved numerically by a Fourier analysis of the resulting unknown but regular function, and the computed results for the induced currents on the strip are presented.
Multiple Ionization of Cesium and Barium by Successive Electron Impacts
Authors: Redhead P. A. , Gopalaraman C. P.
Published: April 2011

The electron energy dependence of the multiply-charged ion currents of cesium and barium (up to Cs10+ and Ba10+) has been measured in a trapped-ion source mass spectrometer. Approximate values of the higher ionization potentials have been measured which agree with the values predicted by extrapolation methods, to within the combined uncertainty of the experimental and extrapolation methods (~5 V), except for the ionization potential of Ba9+. Improved estimates of higher ionization potentials of ions with atomic number 53–56 have been obtained by the extrapolation method. The energy levels of some long-lived metastable states of Cs and Ba ions were estimated from the measured appearance potential curves.
Contribution to the Theory of Weak Coupling Superconductors
Authors: Leavens C. R. , Carbotte J. P.
Published: April 2011

We have managed to simplify the Eliashberg equations for the case of weak coupling superconductors. Further, an explicit approximate analytic solution of the simplified equations has been obtained for the zero temperature gap edge. An expression for the critical temperature is also given. It is found to be of the BCS form and allows the BCS parameter N(0)V to be identified with a simple function of the normal state properties. The validity of our simplified integral equations and of our analytic solution is established by comparison with numerical solutions of the complete Eliashberg equations. The equations are used to discuss the effect of pressure on the gap, the isotope effect, as well as other properties.
Moment Comparison of Two Decoupling Procedures for Green Function Equations
Authors: Frank Barry
Published: April 2011

A recently developed moment theorem and an approximation scheme of Pryce and Stevens are used to compare 2nd-RPA and Tomita–Tanaka type decoupling procedures for Green function equations. The comparison is accomplished from the point of view of the moments of the paramagnetic resonance line shapes that the decouplings generate. An Ising system in an external magnetic field is taken as the model system. It is found that use of the more complicated 2nd RPA is justified only if accuracy to O(1/z2) is desired.
Temperature Dependence of Neutral Donor Scattering
Authors: Sinha Om P.
Published: April 2011

The applicability of the Friedel sum rule and its importance in the neutral impurity scattering in semiconductors has been examined. A formula due to Mattis and Sinha using the Friedel sum rule and multichannel scattering in multi-valley semiconductors has been reproduced and compared with the recent experimental results on τn by Blagosklonskaya et al. as well as the theoretical formulas by these authors and others.
Improved Values of the E2/M1 Mixing Ratios of the 22+ → 21+ Transitions in 126Te and 126Xe
Authors: Taylor H. W. , Singh B.
Published: April 2011

A new determination of δ for the 22+ → 21+ 754.0 keV gamma transition in 126Te and the 22+ → 21+ 491.3 keV transition in 126Xe has been carried out with a Ge(Li)–NaI(Tl) directional correlation spectrometer. The values[Formula: see text]are a substantial improvement over previous measurements. The difference between the proton and neutron deformations of the first 2+ state of 126Te is deduced.
Twilight Airglow Measurements of the OH and O2 Bands by Means of Balloon-Borne Instruments
Authors: Pick D. R. , Llewellyn E. J. , Jones A. Vallance
Published: April 2011

A gondola carrying a grating spectrometer for the 1–2 μ region and filter photometers with pass bands at 1.27 μ and 1.66 μ was flown from Fort Churchill. The equipment was maintained at a height of 42 km through evening and morning twilights. The variation of the O2 IR atmospheric band at 1.27 μ was measured for morning and evening high latitude summer twilight. The evening decay was faster than predicted theoretically. An experimental value of 80 ± 15 obtained for the intensity ratio between the 0,0 and 0,1 IR atmospheric bands. A measurement of the morning and evening twilight variation of the 5,3 OH band was obtained
Positron and Positronium Lifetimes in Liquid Argon
Authors: Spektor Dalia M. , Paul D. A. L. , Stevens J. R.
Published: April 2011

New results for positron lifetimes in liquid argon confirm earlier results of Paul and of Liu and Roberts. In particular the orthopositronium intensity is anomalously low in this liquid, only 7%. It is shown by experiment that the high singlet positronium and intensity found by Briscoe, Choi, and Stewart could have been due to oxygen impurity.
Study of the 48Ti(α,p)51V and 50Ti(3He,d)51V Reactions
Authors: Maheshwari P. N. , Gupta U. C. , St-Pierre C.
Published: April 2011

The reactions 48Ti(α,p)51V at ten bombarding energies between 8.25 and 10.75 MeV and 50Ti(3He,d)51V at 10 MeV bombarding energy have been studied. Energy levels of 51V up to 4.85 and 6.17 MeV have been observed by (α,p) and (3He,d) reactions respectively. The (α,p) reaction yielded many new energy levels. The angular distributions for deuterons were measured at lab angles between 15° and 120°, and compared with predictions of DWBA calculations using the TSALLY code from which the transferred angular momenta and spectroscopic factors were deduced. These experimental results are examined from the viewpoint of shell model and strong coupling rotator model calculations. The effect of changing various optical model parameters is also discussed.
K Conversion Coefficient of the near Threshold M3 Transition in 191Os
Authors: Campbell J. L. , O'Brien P. , McNelles L. A.
Published: April 2011

The K conversion coefficient of the predominantly M3 transition at 74.37 keV in 191Os has been measured to be 75 ± 8. This differs both from the theoretical value of 160 and a recent measurement giving 38.4.
Correlation between Ion and Electron Probe Currents in a Turbulent Plasma Flow
Authors: Ghosh A. K. , Richard C. , Johnston T. W.
Published: April 2011

An experimental investigation for the justification of using the electrostatic probes for turbulent plasma diagnostics is discussed. The object is to find how faithfully the probe current fluctuations follow the electron density fluctuations, since in general it is a function of other parameters such as temperature, plasma potential, flow velocity, and gas pressure. The procedure adopted is to study the instantaneous correlation between probes which are close to each other operating in three different modes (single ion probe, single electron probe, and double probe). The probe currents in these three modes will all have the electron density multiplied by expressions differently dependent on other parameters. Excellent instantaneous correlation observed is a persuasive indication that the probe current fluctuation is indeed a measure of the electron density fluctuation. An instantaneous correlation between an ion probe and the floating potential of another probe shows hard diode-type characteristics, the true significance of which is not fully understood.
Measurement of Intermediate Energy Gamma-Ray Cross Sections
Authors: Henry L. C. , Kennett T. J.
Published: April 2011

Gamma-ray cross sections for 30 well-distributed energies from 121 keV to 10.827 MeV in 9 target elements ranging from carbon to uranium have been measured with an accuracy of better than 1%. Deviations from recently quoted theoretical cross sections were observed in the energy region from 6–11 MeV, particularly for high-Z target materials. The approximately Z2 dependent deviations are certainly associated with the elastic pair-production process, the present opinion being that they arise from an overestimation of the effects of atomic–electron screening on the pair cross section in the intermediate energy region.
Some Hartree–Fock Results for (3d + 4s)q+1 Configurations
Authors: Fischer Charlotte Froese
Published: April 2011

Self-consistent field calculations have been performed in three different ways for the average energy of the configurations 3dq−14s2, 3dq4s, and 3dq+1, q = 2,3,..., 9 of the neutral atoms scandium to nickel. The calculations differ in the way the radial functions depend on the configuration. Parameters which enter into the interaction matrix for states of these configurations are reported. It is shown that the lack of orthogonality of an orbital from one configuration with that of another may alter the interaction matrix element significantly, and that the parameters for radial functions independent of the configuration are significantly different from those that depend on the configuration.
Comptage des Photoélectrons Provenant de Points Statistiquement Indépendants et d'une Surface Etendue de la Photocathode
Authors: Bures Jacques , Delisle Claude
Published: April 2011

The experimental photocount distribution from a photocathode illuminated by a pseudothermal source is compared with theory. The detection time is much smaller than the coherence time [Formula: see text]. The agreement is excellent for an illuminated area composed of holes small enough to be considered as points and far enough to guarantee incoherence among them. But, for an extended circular area, the agreement is good only in the limits when that area is very small or very large with respect to the coherence area. Finally, we consider on the one hand, the evaluation of an extended detection area as a function of the number of statistically independent points, L, and on the other hand, the relative size of a physical point.
Matrix Method to Study Open Resonators; Expansion in Jacobi's Polynomials
Authors: Bélanger P. A. , Tremblay R.
Published: April 2011

A method to solve the integral equations found in the theory of open resonators is presented. This method, based on the expansion in terms of orthogonal polynomials, reduces the problem to finding the eigenvectors and eigenvalues of a matrix. The final matrix is a product of three matrices. Simple methods to calculate these matrices by recurrence or directly are given. Examples of the choice of the polynomials suitable for small Fresnel numbers are included.
Pressure-Induced Infrared Absorption of Gaseous Hydrogen and Deuterium at Low Temperatures. III. Further Analysis of the Fundamental and First Overtone Bands of Hydrogen
Authors: Watanabe A.
Published: April 2011

Pressure-induced infrared spectra of hydrogen in the fundamental region, recorded at 18, 20.4, and 24 K, have been reanalyzed making use of recently calculated theoretical matrix elements of the polarizability and the quadrupole moment of hydrogen. The analysis revealed a density dependence in the relative intensities of the single and double transition quadrupolar induced components. This density dependence was used as a correction to improve the analysis of the first overtone spectrum, obtained at 24 K with a density of 31 amagat. The observed and calculated spectra then agreed to a satisfactory degree except for a discrepancy in the intensity of the Q1(1) + Q1(J) components for which no satisfactory explanation could be given.
Final State Interactions in the Reaction T(3He,4He)np
Authors: Beveridge J. L. , Johnson R. R.
Published: April 2011

A triple correlation cross section was measured for the reaction T(3He,4He)np in a complete experiment at a 3He bombarding energy of 1.5 MeV. The Watson–Migdal and Phillips, Griffy, and Biedenharn (PGB) final state interaction theories are compared in the analysis of the experimental data. The Watson–Migdal theory gives a good description of both the 5He ground state and singlet n–p cross section enhancements. One form of the PGB theory gives a prediction of the singlet n–p enhancement which is indistinguishable from the Watson–Migdal prediction in this experiment. The measured cross section was found to be dominated by direct statistical breakup and sequential decay through a virtual singlet n–p state and the ground state of 5He. A singlet n–p scattering length of [Formula: see text] was determined from the analysis of the three-body data. The reaction T(T,4He)2n is similar to the reaction T(3He,4He)np. Consequently using a complete experimental technique to estimate the anns from T(T,4He)2n would lead to similar error estimates, i.e. [Formula: see text].
Radiative Width of the 6+ Level in 20Ne at 8.78 MeV
Authors: Rogers D. W. O. , Aitken J. H. , Litherland A. E. , Dixon W. R. , Storey R. S.
Published: April 2011

The radiative width of the 6+ resonance at Eα = 5.06 MeV in the 16O(α, γ)20Ne reaction has been measured to be ωγ = 1.30 ± 0.20 eV corresponding to a transition strength of 20 ± 3 W.u. for the 6+ to 4+ transition in 20Ne. Comparison is made to rotational and shell model predictions.
Determination of the Electrical Radius ka of a Spherical Scatterer from the Scattered Field
Authors: Boerner W. M. , Vandenberghe F. H.
Published: April 2011

The inverse problem of scattering for a spherical vector scattering geometry is considered. The transverse scattered field components are related to the expansion coefficients of Hansen's vector wave expansion in terms of the scattered field matrix. This matrix needs to be inverted to obtain the unknown expansion coefficients which are required to recover the shape of the target in question. Since the particular properties of the spherical vector wave expansion may cause highly instable matrix inversion, an analytical, closed form solution of the determinant associated with the scattered field matrix was sought. For vector scattering geometries representing the mth degree multipole cases such closed form solutions for the associated determinant of truncated order 2N are derived, using a novel complementary series expansion for the employed forms of the associated Legendre's functions of the first kind. A novel determinate optimization procedure is presented which enables the specification of the optimal distribution of measurement aspect angles within any given finite measurement cone of the unit sphere of directions. The closed form solution for nonsymmetrical vector scattering geometries is presented in Appendix III only for the value N = 3 (m = 0 and 1) employing properties of quadratic forms as derived in Appendix II. It is then shown that the electrical radius ka of a perfectly conducting spherical scatterer can be directly recovered from a finite number of contiguous expansion coefficients similar to the cylindrical case presented in Boerner, Vandenberghe, and Hamid. Furthermore, relationships between contiguous expansion coefficients of both electric and magnetic type result, which are relevant to the general inverse problem since the scattered field can be uniquely expressed in terms of only one set of expansion coefficients associated with either the electric or magnetic vector wave functions.
Acoustic Phase Velocity Measurements along General Directions in Non-Isotropic Crystals. I. Elastic Properties of Monoclinic K3Co(CN)6
Authors: Chou T. H. , McBride S. L. , Rumin N.
Published: April 2011

The complete elastic constants tensor of monoclinic potassium cobalticyanide [K3Co(CN)6] has been determined from measured ultrasonic phase velocities. These were obtained as a function of direction in several crystal planes by measuring the acoustic energy reflection coefficient at a liquid–solid interface as a function of angle and plane of incidence. The measurements were made at 27.6 MHz in p-xylene at 21.5 °C. The elastic constants were determined using an existing perturbation method. Velocities calculated from the derived elastic constants are in agreement with the measured velocities to within experimental error and the approximations in the perturbation calculation. The usefulness of this method for the determination of the elastic constants of low symmetry crystals is thus established. The Debye temperature of K3Co(CN)6 is estimated from the results to be 290 ± 10 °K with a corresponding mean acoustic velocity of 2560 ± 80 m/s.
Drift Instability in the Presence of Nonuniform Radial Electric Fields
Authors: Capjack C. E. , Stringer T. E.
Published: April 2011

An equation describing the drift instability in a collisionless low-β plasma, in the presence of a nonuniform radial electric field is derived from guiding center equations for the ions and the drift kinetic equation for the electrons. Numerical solutions to this equation indicate that the influence of a nonuniform radial electric field on the drift instability may be determined from the manner in which this field modifies the macroscopic electron rotation profile.
Lattice Refrigeration below 10−3 °K
Authors: Kos J. F.
Published: April 2011

A method is proposed whereby the lattice of some piezoelectric materials may be cooled below 10−3 °K and possibly as low as 3 × 10−6 °K.
Sur la Mise en Evidence de Faibles Branches β dans la Désintégration de 77As
Authors: Ardisson G. , Marsol C.
Published: April 2011

The decay of 77As was reinvestigated by means of a Ge(Li) detector, γ–γ coincidences and sum coincidence spectra were also measured with a Ge(Li)–NaI(Tl) assembly. Five new gamma rays are observed at 62.2, 82.0, 139.2, 200.6, and 439.7 keV, which are situated in a revised level scheme of 77Se. An anomalous 5/2+ level of 301 keV, seen in 76Se(d,p)77Se experiments, is suggested to be fed in the decay of 77As, with a branching ratio of 0.014%. The 440 keV (5/2−) collective level is also fed by 0.001% of the decays.
Charge-Exchange Scattering of Pions on 14N
Authors: Maclin Arlene P. , Eisenberg J. M.
Published: April 2011

Cross sections for the reaction 14N(π+,π0)14O are calculated near the (3, 3) resonance using the impulse approximation together with the Chew–Low amplitude in the framework of a two-hole shell model formalism. Various sets of wave functions are used and comparisons are made with existing experimental data and other theoretical calculations.
Electron Spin–Spin Contact Interaction in Atoms with fn Configurations
Authors: Saxena K. M. S. , Lo B. W. N. , Fraga S.
Published: April 2011

The expressions of the matrix elements of the electron spin–spin contact interaction have been tabulated for all the states arising from fn configurations. Numerical calculations have been carried out for a large number of lanthanide atoms and ions using accurate numerical Hartree–Fock functions.
Spectromètres Electrostatiques. Partie III
Authors: Roy D. , Carette J.-D.
Published: April 2011

The method of calculating the energy distribution of electrons selected electrostatically, presented in Part I, has been used to calculate the distribution profiles for principal electrostatic spectrometers: toroidal, cylindrical 127° and spherical 180° spectrometers, parallel plate and cylindrical mirrors. The calculations have been performed as a function of the most important geometrical parameters of the spectrometers: the slit width and the angular aperture. They have been made in a generalized form by expressing these geometrical parameters as a function of the main dimension of each apparatus: main radius in the case of toroidal-type spectrometers, distance between the slits in the case of mirrors. In this way results presented may be extended to spectrometers of any size. Similarly as calculations have been performed for a nominal energy of the electron beam of 1 eV, the energy scale may be considered as arbitrary and it suffices to multiply it by the nominal energy of interest. For each type of spectrometer, equations used in calculations are given. For various slit widths and angular apertures of spectrometers, numerous energy distribution profiles are presented with the usual characteristics of energy distribution, that is half-intensity width (FWHM or [Formula: see text], base width (FWB or ΔEB), and arbitrary transmitted current (It).
Elastic Strain Energy of Dislocations in Ice
Authors: Tyson W. R.
Published: April 2011

The energy stored in the elastic strain field of dislocations in hexagonal ice is calculated using anisotropic elasticity and the most complete set of elastic constants available. Ice is elastically fairly isotropic, and it is proposed that the high mobility of dislocations on the basal plane is due to dissociation of perfect dislocations on this plane.
A Channeling Study of the Structure of U4O9
Authors: Matzke Hj. , Davies J. A. , Johansson N. G. E.
Published: April 2011

The channeling behavior of 1-MeV He+ ions and deuterons in U4O9 has been studied in order to provide information on the location of the excess oxygen in the fluorite structure of UO2. Wide-angle (Rutherford) scattering was used to study the channeling behavior with respect to the uranium sublattice, and the 16O(d, p)17O reaction was used to investigate the oxygen sublattice. A pronounced disorder in the oxygen sublattice was indicated by very poor channeling properties and strong dechanneling with increasing depth. The data are thus in conflict with the model incorporating the excess oxygen in the regular interstitial positions along the [Formula: see text] uranium rows; on the other hand, they are consistent with the more recent model of Willis in which the excess oxygen atoms are displaced ~ 1 Å from the regular interstitial sites and displace, in addition, some normal oxygen atoms. Channeling with respect to the uranium sublattice was found to be substantially the same as in stoichiometric UO2—but with a somewhat smaller critical angle, indicating that the uranium atoms may be displaced slightly (i.e. ~ 0.25 Å) by the presence of the excess oxygen.
Etude de l'Effet des Paramètres d'Appareil sur la Décroissance de la Visibilité du Spectre Cannelé
Authors: Delisle C. , Brochu M. , St-Arnaud J. M.
Published: April 2011

The visibility of the channelled spectrum, or in other words the visibility of the spectral density modulation at the exit of a Michelson interferometer illuminated with a parallel beam of white light, is theoretically independent of the frequency and path difference of the two beams formed in the interferometer. Up to now there has been no agreement between theory and experiment. It is shown here, theoretically and experimentally, that the decrease in visibility with increasing path difference is related to both the finite size of the slits and the limit of resolution of the apparatus.
Dependence of the Depolarization Tensor on the Displacement Gradient
Authors: Redlack A. , Grindlay J.
Published: April 2011

Expressions are given for the first- and second-order derivatives of the depolarization tensor with respect to the displacement gradient. The results are applied to the special case of the sphere.
Simplified Method for the Calculation of Characteristic Temperatures of Diamond and Sphalerite-Structure Solids
Authors: Reeber R. R. , McLachlan Jr. D.
Published: April 2011

Characteristic temperatures of crystals having the diamond and sphalerite crystal structures were calculated by use of a model based on lattice theory. In the calculations the elastic longitudinal mode of vibration in the [Formula: see text] crystallographic direction has been directly related to the cutoff frequency of the acoustical part of the lattice-vibration spectrum. Characteristic temperatures so calculated may provide a convenient single parameter for relating the acoustical part of the frequency spectrum to some of the observed physical and thermal properties of these solids.
Absorption Spectrum of the NO Molecule. X. The 3d Rydberg Complex, its Vibrational Structure, Spin–Orbit Coupling, and Interactions with Non-Rydberg States
Authors: Miescher E.
Published: April 2011

The vibrational levels of the 3dσ,π Rydberg complexes of the NO molecule are studied. They give rise to absorption bands 3d–X in the vacuum ultraviolet, most of which are severely overlapped by other bands, and, in addition, to Rydberg–Rydberg emission bands in the visible (3d–3s) and in the infrared (3d–3p). Both types of spectra have been photographed at high resolution, the absorption spectra for three different isotopes.Interactions with non-Rydberg levels and predissociations are observed. A detailed analysis, including spin–orbit effects, is given of the crossing between the 3dσ,π(ν = 1) and B2Π(ν = 23) rotational levels. Off-diagonal matrix elements are determined and precise vibrational and rotational constants are calculated. Largely responsible for the unusual structure of the bands is the matrix element [Formula: see text] which is shown to be independent of ν.
Hyperfine Structure in Excited Levels of the Arc Spectrum of Bismuth
Authors: Dickie L. O. , Kelly F. M.
Published: April 2011

The hyperfine structure of a number of excited 4P1/2 levels of neutral bismuth have been measured and the results compared with theory.
Levels in 35Cl: Theoretical
Authors: Wiesehahn W. J.
Published: April 2011

The experimental results obtained for 35Cl are interpreted in terms of the shell model with core excitations. The states at 3165 and 7545 keV are [Formula: see text] states. The states at 4174 and 7841 keV are [Formula: see text] states. In both cases the higher energy state is the isobaric analogue of a state in 35S. All other states below 6 MeV may possibly be described as an excited core to which is coupled a [Formula: see text] proton. This particularly explains the extreme retardation of the transition between the 3164 and 2645 keV states.
Energy Spectra of keV Backscattered Protons as a Probe for Surface-Region Studies
Authors: Wijngaarden A. van , Miremadi B. , Baylis W. E.
Published: April 2011

Energy spectra have been measured of 1H and 4He projectiles backscattered from thin Au films of known thicknesses. An analytical expression for the spectra is derived in the limit of no multiple scattering. Protons of energies ~50 keV are shown to give resolutions of a few Å for depth measurements up to about 500 Å, thus providing a useful technique for studying surface regions. The technique is illustrated by measurements of a nickel film before and after oxidation. Stopping cross sections for 1H and 4He in Au are obtained for energies 20 < E < 100 keV.
The Effect of Alloying on the Fermi Surface of Copper. II. Electron-scattering and Neck Cross Sections with Dilute Heterovalent and Transition Metal Solutes
Authors: Coleridge P. T. , Templeton I. M.
Published: April 2011

The Fermi surface neck size and the scattering cross sections for the neck and [Formula: see text] belly orbits have been measured in dilute alloys of Zn, Al, Ge, Si, Ni, Co, Fe, Mn, and Cr in Cu. Earlier observations of rigid-band behavior for the neck size in Cu(Zn) and Cu(Al), while essentially substantiated by the present measurements, are now believed to be fortuitous; Cu(Ge) and Cu(Si) do not agree with a rigid-band prediction. The changes (generally reductions) of neck size in the transition metal alloys do not appear to be related directly to changes of electron concentration. The scattering anisotropy is rather small in the heterovalent alloys, the scattering being somewhat greater on the necks, but is large and in the opposite sense in the transition metal alloys. The magnitude and anisotropy of scattering is interpreted in terms of phase shifts associated with the impurities and the wave functions over the Fermi surface. There is evidence for additional scattering anisotropy in alloys exhibiting the Kondo effect.
Polarized Orbital Calculations of Positron Collisions with Lithium Atoms
Authors: Dai Bui Tien , Stauffer A. D.
Published: April 2011

The collision of positrons with lithium atoms is treated by the polarized orbital method. Results of calculations for the elastic and diffusion cross sections, Zeff, and the angular correlation function are given.
Rotational Analysis of the C2Π → X2Σ+ Electronic Transition of LaO
Authors: Green David W.
Published: April 2011

A rotational analysis of the 0–0 band of the LaO C2Πr → X2Σ+ transition near 4400 Å has revised the previously reported analysis. It is demonstrated that the C2Π state is also the upper state of previously analyzed bands near 6500 Å. It is shown that the X state of LaO is 2Σ+ and that an interaction between the unpaired electron and the La nuclear spin causes a doubling (0.51 cm−1) of each rotational level. This splitting appears to show a slight rotational dependence and a negligible vibrational dependence. The coupling of the X2Σ+ state is nearly pure case bβS. The C2Πr state exhibits a large Λ doubling. The 0–0 subband origins are at 22 839.61 for the C2Π3/2 → X2Σ+ and 22 618.87 cm−1 for the C2Π1/2 → X2Σ+. Rotational spectroscopic constants are reported.
Spin–Parity Combinations in 18O
Authors: Ollerhead R. W. , Allen G. F. R. , Baxter A. M. , Kuehner J. A.
Published: April 2011

Detection of inelastically scattered alpha particles near 180° from the reaction 18O(α,α′)18O has been used to identify natural parity levels in 18O. Energy spectra were recorded for 13 incident energies from 20.0 to 23.4 MeV. Levels at 4.45, 5.09, and 5.25 MeV have been identified as having natural parity, confirming earlier assignments of 1−, 3−, and 2+, respectively. Levels at 5.37 and 5.52 MeV have been identified as having unnatural parity leading to definite assignments of 3+ and 2−, respectively. The spin and parity of the 6.18 MeV level has been restricted to 1− or 2+. Other levels at higher excitation energies have been assigned natural parity, and the implications with regard to the identification of a negative parity band in 18O are discussed.
APW Calculation for Band Structure of Cadmium
Authors: Pendyala Subrahmanyam , Pant M. M. , Tong B. Y.
Published: April 2011

An APW calculation of the band structure of cadmium is reported. The calculated band structure is similar to that obtained by others from pseudopotential calculations and explains some of the observed peaks in the optical absorption spectrum in terms of direct transitions.
Static Magnetization Studies on the Family of Compounds Cd1−xFexCr2S4
Authors: Spender M. R. , Morrish A. H.
Published: April 2011

Static magnetization measurements have been made on a number of compounds in the family Cd1−xFexCr2S4 for [Formula: see text]. The magnetic moments at 0 °K fall with increasing iron content. The ordering temperatures rise and the Curie–Weiss parameters fall with increasing iron content. There is a steady decrease in lattice parameter with increasing x. A simple model is proposed in which the extra antiparallel electron on the Fe2+ ion is delocalized. The band in which the electrons move is assumed to have a trap for electrons in the vicinity of the A sites. The trap allows ionic behavior at low temperatures while at higher temperatures the electrons are itinerant. The model allows a consistent understanding of the magnetic properties.