bluuebunny/crossref_metadata_2025 huggingface dataset:
Reaction mechanism of the 16O + d reactions
Authors: Davison N. E. , Dawson W. K. , Roy G. , McDonald W. J.
Published: April 2011

The reactions 16O(d,d)16O, 16O(d,p)17O, and 16O(d,n)17F have been studied in the deuteron energy range 4.00–6.00 MeV in order to determine to what extent current theories can satisfactorily describe these reactions. It was found that the theoretical curves from both the optical and DWBA models fit the experimental data significantly better when the deuteron optical-model potentials had been obtained using a spin–orbit potential in the analysis of the elastic scattering data. Spectroscopic factors obtained for the ground and first-excited states of 17O and 17F using the DWBA theory are in satisfactory agreement with theoretical predictions and with values obtained by previous workers. Small, but nonzero, spectroscopic factors have been obtained for the states at 3.058 and 3.846 MeV excitation in 17O using data measured in this work and in previous experiments. The sum of the calculated direct interaction and compound-nucleus cross sections is in good agreement with experimental data for all states studied, whether they were populated primarily by direct or compound-nucleus reactions. The calculated compound-nucleus lifetimes are also in agreement with values obtained from an analysis of the fluctuations in the yield curves.
Excited states in 75As
Authors: Paradellis Th. , Hontzeas S.
Published: April 2011

The gamma-ray spectrum of 75Se has been studied with a variety of Ge(Li) detectors. The energies and intensities of 15 lines have been accurately measured. Of these a 24.4 and 468.6 keV transition were substantiated for the first time in the gamma-ray spectrum. Ge(Li)–Ge(Li) coincidence measurements established the newly observed 24.4 keV transition. These experiments also substantiated the 80.8 keV transition (observed for the first time) deduced from electron conversion spectra. The accurate intensity values obtained in this work have been combined with proper literature data and conversion coefficients for various transitions have been determined. These data and recent half-life measurements of some excited states by other workers permitted us to calculate the transition rates in 75As. The data obtained indicate that the 198.6, 279.5, and 400.5 keV levels in 75As exhibit strong collective character, in contrast to the 264.6 keV level, which shows little influence of collective effects.
Relative intensities of the O2+ 1NG and N2 1PG band systems in normal and type-B aurora
Authors: Harris F. R. , Peterson R. N. , Bradley D. T.
Published: April 2011

A wavelength scanning spectrometer has been used to study the intensities of selected O2+ 1NG and N2 1PG bands in the visible spectra of normal and type-B aurora. Peak differential brightnesses are considered. It has been found that I (O2+ 1NG)/I(N2 1PG) is constant to within 70% in both normal and type-B aurora of intensities IBC I through IBC III. The relevance of these observations, in view of previously published results on the subject of type-B aurora, is discussed.
Evidence of configuration interaction in the internal acceptor states in silicon
Authors: Bhatia K. L. , Bichard J. W.
Published: April 2011

The effect of the interaction between a quasi-discrete state and an overlapping continuum of states has been identified in the experimental investigation of the internal acceptor states of Group III impurities in silicon. The effect of the impurity–impurity interaction on the line shape of the boron, gallium, and indium internal acceptor lines has been studied. The observed characteristic asymmetric line shape is explained by introducing the interaction of the internal state with the degenerate P3/2 valence band Bloch states, and the inhomogeneous impurity–impurity interaction. The ionization energy of the substitutional impurity in the host lattice is found to be a deciding factor in this interaction. An estimate of the nonstationary lifetime for the boron internal state, 2p′, has also been made.
Some Doppler-shift lifetimes in 30P
Authors: Lachaine A. , Hird B.
Published: April 2011

The Doppler-shift attenuation method has been used to determine some lifetimes in 30P which are populated by the decay of resonances in the 29Si(p,γ)30P reaction at 1505, 1643, and 1686 keV, and the 1773–5 keV doublet. There is evidence that either the 1775 keV component of the doublet has a measurable lifetime of 10 ± 5 fs or that all the observed radiation from this doublet contains γ rays from both components.
Réaction séquentielle 11B(p,α)2α
Authors: Goulard Gisèle
Published: April 2011

An extensive study is made of the formula derived for the differential cross section of a sequential reaction A + B → C* → D + G* → D + E + F, Numerical results are obtained for incident energies of 163 keV, 680 keV, 2 MeV, 2.65 MeV and compared with different experimental data.
Scale invariance and the energy–momentum tensor
Authors: Bendix Peter
Published: April 2011

A method is described by which an energy–momentum tensor can be constructed such that in addition to the usual properties of this tensor it acquires the property of scale invariance in the absence of masses and charges. (The new energy–momentum tensor constructed here is not the source of the gravitational field, however.) It is shown that the usual construction for the massless Klein–Gordon field yields an energy–momentum tensor which is not scale invariant, whereas using the construction described here, one finds a scale invariant energy–momentum tensor for this case.
Model for γ decay of atomic or nuclear systems
Authors: Razavy M. , Henley Jr. E. A.
Published: April 2011

An exactly solvable quantum-mechanical model for interaction of a spinless bound particle with the electromagnetic field is studied. This model is used to calculate the electromagnetic transition in atomic and nuclear systems. Some general results as to the dependence of line width and level shift on the binding potential are obtained.
Temperature and pressure variation of the 35Cl nuclear quadrupole resonance frequency in K2OsCl6
Authors: Armstrong Robin L. , Baker Gregory L.
Published: April 2011

Measurements of the temperature and pressure dependence of the 35Cl nuclear quadrupole resonance (NQR) frequency in K2OsCl6 are reported. The resonance frequency is measured at atmospheric pressure for temperatures from 4.2 to 430 °K and for five temperatures between 284 and 410 °K for pressures to 5000 kg cm−2. A second-order phase transition occurs at about 45 °K. In the high temperature phase all of the chlorine atoms are crystallographically equivalent. The analysis carried out deals exclusively with the data obtained in this phase. A thermodynamic relation is used to relate the experimental quantities (∂v/∂T)P and (∂v/∂P)T to the theoretical quantity (∂v/∂T)V. The latter quantity is calculated for a particular model to describe the motional averaging of the electric field gradient at the chlorine sites. The model adopted includes two distinct mechanisms—the usual Bayer–Kushida averaging mechanism and a mechanism resulting from the partial destruction of π bonding by the lattice vibrations. The thermodynamic relation is used in conjunction with the combined data for K2PtCl6, K2IrCl6, and K2OsCl6 to evaluate the validity of the model proposed. It is concluded that the model provides a consistent explanation of both the temperature and pressure variation of the NQR data. In addition, the analysis provides information on the nature of the molecular orbitals of the [MCl6]2− complex ion, gives a rough estimate of the ratio of the coefficient of thermal expansion to the isothermal compressibility, and lastly, yields a value for the average frequency of the rotary lattice mode in the three substances.
Gamma-ray polarization measurements in 22Na
Authors: Baxter A. M. , Gillespie B. W. J. , Kuehner J. A.
Published: April 2011

The 19F(α,nγ)22Na reaction was studied using a Ge(Li) single-crystal polarimeter in addition to conventional Ge(Li) counters to elucidate certain spin, parity, and multipole-mixing ratio assignments to low levels of 22Na. The 1.984 MeV level, which had previously been assigned 2+ or 3+, has been shown not to be 3+ and, while 2+ is favored by the experiment, the evidence tends to suggest a problem in the interpretation of the properties of this level. The 2.572 MeV level is shown most likely to have spin and parity 2+. The J = 2 level at 3.059 MeV is clearly established as having even parity. In several cases limits on mixing ratios are obtained. These results cast doubt on certain model identifications made recently in 22Na.
Dependence of geomagnetic activity on the polarity of the interplanetary magnetic field
Authors: Hruška A. , Hrušková J. , Jacobs J. A.
Published: April 2011

Geomagnetic activity measured by the Kp index varies with the angle α between the Earth–Sun vector and the vector of the interplanetary magnetic field. The effect is due to the change in magnitude and in fluctuations of the magnetic field with α.
Critical point analysis of cubic ZnS
Authors: Irwin J. C.
Published: April 2011

An interpretation of the second-order Raman and infrared spectra of cubic ZnS is given. A set of values is obtained for the phonon frequencies at the zone boundary critical points X, L, and W. These values are consistent with both the experimental results and a theoretical model. The frequencies obtained are compared with those proposed by previous workers.
Atmospheric refractometry at high relative humidities
Authors: Turner H. E. , Hay D. R.
Published: April 2011

Precise measurement of changes in air refractivity is provided by the high-frequency (h.f.) refractometer at relative humidities below 50%. Above this limit, the indicated refractivity may exceed the true refractivity by an amount that increases with humidity. The experimental techniques of gravimetry, ellipsometry, and photomicrography are combined with refractometer observations in a controlled environment to study the source of this anomaly. It is found that the anomaly is due to the added polarization of a layer that forms progressively upon the sensor surfaces, that the layer growth is insensitive to the h.f. electric field, and that the layer density lies between that of moist air and of bulk water while its depth increases to some 1500 Å near saturation humidity. At humidities above 90%, microscopic water droplets also form on the sensor surfaces. These observations are attributed to vapor adsorption and condensation on the sensor, with the latter related to surface asperities; the relative contribution of these two components in the layer structure depends upon the method by which the environment has been humidified.
Two sphere model for the asymmetric division of electrically charged liquid drops
Authors: Ryce S. A. , Wyman R. R.
Published: April 2011

For the binary division of electrically charged liquid drops a (pseudo) saddle point configuration is considered consisting of two spheres of radii r1 and r2, a distance α(r1 + r2) apart.Computation of surface energy and Coulomb energy terms shows that an asymmetric configuration, i.e., r1 ≠ r2 is energetically favored for all values of the fissionability parameter [Formula: see text], where x is defined as x = Q2/16πR3γ for the original drop with charge Q, radius R, and surface tension γ. Minimization of the energy terms requires a charge transfer directed towards the smaller sphere.Uniform, but not necessarily equal, surface charge is assumed for the two-sphere configuration. A more exact solution involving image charges gives very similar results.The present results for sphere separations α = 1 to α = ∞ confirm previous work in which a value of α = ∞ only was considered.
Interpretation of Ti3+ electron spin resonance spectra in alums
Authors: Manoogian A.
Published: April 2011

It is postulated that Ti3+ exists in 12 differently oriented, but otherwise equivalent, magnetic complexes in CsTi(SO4)2∙12H2O and titanium-doped CsAl(SO4)2∙12H2O alums. This explanation appears to clear up the discrepancy between the theory and the experimental g values found by ESR measurements. The analysis indicates that the titanium ion in alums exhibits a particular class behavior and this is true whether the titanium exists in dilute or concentrated form.
On the mass distribution of faint sporadic meteors
Authors: Jones J. , Collins J. G.
Published: April 2011

Forward scatter and backscatter determinations of the amplitude distributions of underdense sporadic radio meteor echoes are described. The experimental results lead to an ionization distribution index of 3.13 and are shown to be consistent with an initial train radius of about 80 cm at a height of 100 km. Comparison of the ionization and luminosity distributions of meteor trains indicates a small mass dependence of the geocentric meteor velocity, which we suggest is due to the mass distribution index of meteoroids in retrograde orbits being higher than that of the meteoroid population as a whole.
Simulation of complex dielectric structures
Authors: Fedotowsky A. , Boivin G. , Sen A. K. , Tremblay R.
Published: April 2011

Methods for simulating dielectric targets having a continuous variation of the dielectric constant for microwave scattering purposes are described. Experimental results are also presented.
Elastic scattering of 100 MeV protons from 3He and 4He
Authors: Goldstein N. P. , Held A. , Stairs D. G.
Published: April 2011

Elastic scattering of 100 MeV protons by 3He and 4He has been measured over a wide range of angles. Analysis of the small-angle results was carried out using a superposition of nucleon-nucleon amplitudes computed with both modern and old phase shifts. No significant differences were found in the accuracy of the predictions resulting from the two sets, but in both cases the 3He results were better than those of 4He. The peaking evident in the backward p–4He scattering but not seen in heavy nuclei has been interpreted in terms of an exchange interaction using an optical model analysis.
Generation of an acoustic pulse by absorption of radiation
Authors: Cross R. C. , Ardila R.
Published: April 2011

Profiles of the pressure disturbance created in oxygen by the absorption of a strong beam of light have been obtained experimentally. A comparison is made with theoretical predictions based on the method of characteristics.
Hole mobility in Cu2O. II. Scattering by defects
Authors: Kužel R. , Cann C. D. , Sheinin S. S. , Weichman F. L.
Published: April 2011

The mobility of holes in Cu2O was measured and for certain types of samples found to be very much lower than could have been expected from scattering by lattice phonons. It is proposed that large (10−10 cm2 or greater) space charge limited centers are responsible since these will give the right temperature dependence of the mobility and are compatible with barrier layers around the crystalline copper precipitates present in all samples of Cu2O studied under the electron microscope. The decrease in mobility after heat treatment is explained as resulting from an increased thickness of the depletion layer and resultant increase in size of the scattering center.
Effect of phonons on the e+–e− annihilation rate in metals
Authors: Hede B. B. J. , Carbotte J. P.
Published: April 2011

An estimate of the effect of positron–phonon and electron–phonon interactions on the positron partial annihilation rate in metals is presented in an effort to explain the smearing of the two-photon counting rate at the Fermi cutoff which remains at low temperatures. The lowest-order phonon diagrams in the expansion of the electron–positron correlation function are studied. It is found that such phonon effects do not account for a significant part of the smearing. In fact, it seems sensible to assume that even a more complete treatment of phonon diagrams would not appreciably change this result.
Pulse techniques in ultrasonics
Authors: Law A. K.
Published: April 2011

Some technical problems involved in the measurement of ultrasonic attenuation or absorption with the pulse techniques are discussed and criteria are established on the configuration of the pulse in relation to the properties of the medium under investigation. The problem of harmonics and subharmonics is discussed in detail and measurements (at a frequency of 668 kHz) are made to verify the importance of a correct configuration.
Gain characteristics of an Nd3+ -glass pulsed solid-state laser amplifier
Authors: Douglass H. S. , Campbell C. K.
Published: April 2011

A theory of the four-level solid-state laser has been applied to the case of an unsaturated Nd3+-glass pulsed laser amplifier operating at power levels in the order of 1 MW. Equations for flux density and population inversion have been derived which take into account the degeneracies and splittings of the laser levels. Experiments made with a Q-switched oscillator–amplifier structure validate the predicted exponential dependence of amplifier gain on pumping, over the range of energies applied.
Nuclear g factors of excited 2+ levels in 194Pt
Authors: Kenyon D. B. , Keszthelyi L. , Cameron J. A.
Published: April 2011

The g factors of the 329 and 622 keV levels of 194Pt were measured using perturbed angular correlations of gamma rays in the decay of 194Ir detected with Ge(Li) and scintillation counters. The rotation angles for the two levels are[Formula: see text]in agreement with earlier measurements using scintillation counters. Using recent values for the mean lifetimes of the levels, the g factors are[Formula: see text]
Investigation of some infrared bands of monoiodoacetylene
Authors: Huhanantti Mikko , Anttila Rauno
Published: April 2011

The rotational structures of the ν1 and 2ν1 bands of monoiodoacetylene were investigated. The values B″ = 0.10624 ± 0.00010 cm−1 and D = (3.5 ± 2) × 10−8 cm−1 and B″ = 0.10633 ± 0.00005 cm−1 and D = (1.6 ± 0.6) × 10−8 cm−1, respectively, were obtained from the analyses of these bands. Also the hot bands accompanying these main absorptions were analyzed. In addition lower resolution spectra of some other bands were measured.
Inelastic collisions between excited alkali atoms and molecules. VII. Sensitized fluorescence and quenching in mixtures of rubidium with H2, HD, D2, N2, CH4, CD4, C2H4, and C2.H6
Authors: Hrycyshyn E. S. , Krause L.
Published: April 2011

52P1/2 ↔ 52P3/2 mixing and 52S1/2 ← 52P1/2, 2P3/2 quenching in rubidium, induced in collisions with ground state H2, HD, D2, N2, CH4, CD4, C2H4, and C2H6 molecules, have been investigated using methods of sensitized fluorescence. The rubidium vapor mixed with each of the gases was excited in turn by each component of the rubidium resonance doublet, and the resulting fluorescence, emitted at right angles to the direction of the exciting light, was resolved into the two fine-structure components whose intensity ratios were measured in relation to the gas pressure using photon counting techniques. The measurements yielded the following cross sections for the mixing and quenching collisions.For H2: Q12(2P1/2 → 2P3/2) = 11 Å2, Q21(2P1/2 ← 2P3/2) = 15 Å2, Q10(2S1/2 ← 2P1/2) = 6 Å2, Q20(2S1/2 ← 2P3/2) = 3 Å2.[Formula: see text]The mixing cross sections agree with theoretical values within an order of magnitude.
Switching in amorphous semiconductors
Authors: Armitage D. , Brodie D. E. , Eastman P. C.
Published: April 2011

Switching effects in bulk Te48As30Si12Ge10 amorphous semiconductor have been observed using a planar electrode configuration, with interelectrode spacing of the order of 1 μ. Scanning electron microscope examination of the breakdown region reveals thermal damage, but this may be initiated by an electronic breakdown.
An electron tunneling investigation of quench-condensed superconductors
Authors: Leslie J. D. , Chen J. T. , Chen T. T.
Published: April 2011

An electron tunneling investigation has been carried out on quench-condensed Bi, Ga, Pb, Pb∙75Bi∙25, Pb∙50Bi∙50, and Pb∙25Bi∙75. The energy gap and transition temperature have been measured for each sample. The tunneling derivative data have been analyzed in terms of the strong-coupling theory of superconductivity by means of a computer program of W. L. McMillan. The effective phonon spectrum, the Coulomb pseudopotential, the complex energy gap function, the pairing self-energy function, and the electron renormalization function have been determined for each sample. Certain parameters based on integrals over the phonon spectrum have also been calculated for each sample.
Un spectrométre à réglage automatique permettant l'observation séparée et simultanée de l'absorption et de la dispersion en résonance magnétique nucléaire
Authors: LeBel J. , Paskievici W.
Published: April 2011

not available
Localized canting model for substituted ferrimagnets. I. Singly substituted YIG systems
Authors: Rosencwaig A.
Published: April 2011

A statistical model based on the concept of localized canting, originally proposed by Geller and coworkers, is developed to account for the magnetic properties of substituted ferrimagnets. This model is used to determine the exchange parameter ratios Jdd/Jdd and Jaa/Jad in YIG systems by evaluating the magnetic moments and Curie temperatures of two classes of singly substituted YIG over the entire substitution range. Good agreement with experimental data is obtained with the physically reasonable exchange parameter ratios of [Formula: see text] and Jaa/Jad *~ 0.07. It is also shown that both the Yafet-Kittel and the Nowik models may be regarded as particular limiting cases of the new model.
Damping by extended dislocations
Authors: Blair D. G. , Hutchison T. S. , Rogers D. H.
Published: April 2011

A model in which an extended dislocation jumps about a pinning agent (discussed previously by Blair et al.) gives rise to damping and modulus defect terms. These are calculated for dislocation loops of constant length and for an exponential distribution of loop lengths. The variation of damping and modulus defect with applied cyclic stress and with temperature are deduced and compared with the behavior of a Granato–Lücke breakaway model. The above terms are also calculated for the general problem in which a system "jumps" between two potential wells.
The decay
Authors: Nagpal T. S. , Gaucher R. E.
Published: April 2011

The γ and internal conversion transitions in the [Formula: see text] decay have been examined with Ge(Li) and Si(Li) spectrometers. The measurements of their energies, intensities, K-conversion coefficients, and K/L ratios are used to construct a decay scheme of 125Sb.
Spectral study of the phosphorus glow
Authors: Verma R. D. , Broida H. P.
Published: April 2011

A bright flame produced by the reaction of atomic oxygen with white phosphorus has been developed. In addition to a visible continuum, the emission consists of several transitions of PO and the A1Πg–X1Σg+ transition of P2. Atomic oxygen and a third body such as H2O or H2 is found essential for the production of discrete bands. Pressure effects on the intensity of the β bands of PO indicate the presence of a heterogeneous perturbation in the B2Σ (ν = 7) level by a 2Πr state.
Transport measurements in annealed single crystal tellurium
Authors: Champness C. H. , Kipling A. L.
Published: April 2011

Single crystal samples of tellurium obtained from small diameter ingots, specially grown by the Czochralski method from a melt of the purified element, were studied by measuring the electrical conductivity (σ), Hall coefficient (RH), and transverse magnetoresistance (Δρ/ρ0). As a result of annealing and etching, the Hall mobility (RHσ) and Δρ/ρ0 were substantially increased in the samples at liquid nitrogen temperature, while RH was slightly decreased. The samples were completely intrinsic above 250 °K and at room temperature Δρ/ρ0 was strictly proportional to the square of the magnetic field. Like RH and σ at this temperature, it was also independent of sample history. Two-carrier analysis at room temperature gave electron and hole mobilities of 1890 and 790 cm2 V−1 s−1 respectively. At 77 °K, Δρ/ρ0 in the annealed and etched samples was larger than expected for a simple one-carrier model with a mixture of lattice and impurity scattering.
Gamma-ray yields from the reaction D(p, γ)3He at low energies
Authors: Bailey G. M. , Griffiths G. M. , Olivo M. A. , Helmer R. L.
Published: April 2011

Total cross sections and measurements of the small isotropic component of the γ-ray yield from the reaction D(p, γ)3He have been determined in the energy range from 57 to 1100 KeV using gas and deuterated polyethylene targets. The results are compared with some theoretical predictions.
Surface tension of a Van der Waals fluid
Authors: Strickfaden W. B. , Sobrino Luis de
Published: April 2011

A calculation of the surface tension of simple fluids based on the Van der Waals model of Van Kampen is presented. The result is found to be in excellent agreement with experiment. No adjustable parameters are used.
Anharmonic Specific Heat of Crystalline NaCl
Authors: Kwon T. H. , Henkel J. H.
Published: April 2011

The anharmonic contributions to the specific heat of crystalline NaCl have been evaluated in a localized model characterized by a pseudo potential and direct Brillouin zone sums. The numerical results indicate that the anharmonic contributions to a thermodynamic quantity such as specific heat converge rapidly with respect to the chosen number of normal modes N. The approximately converged results are compared with experiments and with calculations by others.
Calculation on the Self-Trapped Hole in Solid Argon
Authors: Song K. S.
Published: April 2011

Based on a simple model of a hole self-trapped in a VK-center-like configuration, the lattice relaxation, internal optical transition energies, and thermal activation energy for hopping of the self-trapped hole in solid argon are calculated. It is found that the molecular binding of Ar2+ is the predominating factor for the stability of this mode of self-trapping. The optical transition energies are found to be smaller than the corresponding energies in alkali halides. The most interesting result is about the activation energy for hopping which is smaller than 0.05 eV. It is suggested that the self-trapped hole in crystalline argon should be produced and studied at very low temperature, below about 20 °K.
Double Exponential Decay of Imprisoned Resonance Radiation
Authors: Deech J. S. , Baylis W. E.
Published: April 2011

The decay of imprisoned resonance radiation in mercury has been studied using delayed-coincidence techniques. It is characterized by two exponentially decaying components, whose relative amplitudes depend on the direction of linear polarization of the incident radiation. When this direction makes an angle of 54.7° to the direction of observation, only one component is observed. Classical and quantum-mechanical theories are presented which show that the geometry of the scattering cell plays an important role at low atomic densities. Experimental values are presented for the average degree of coherence transferred in the scattering process and for the natural lifetime of the 63P1 state of mercury.
Nuclear Magnetic Resonance Studies of K2CuCl4·2H2O
Authors: Choh Sung Ho , Stager C. V.
Published: April 2011

Nuclear magnetic resonance of 35Cl in paramagnetic K2CuCl4∙2H2O has been investigated in single crystal samples at several different temperatures from 340 °K down to 4.2 °K. Zeeman splitting studies yield the two quadrupole coupling and transferred hyperfine tensors which correspond to the two inequivalent Cl ions. The quadrupole parameters at room temperature are (e2qQ/h)I = 19.05 ± 0.02 MHz, ηI = 0.183 ± 0.001 and (e2qQ/h)II = 3.262 ± 0.006 MHz, ηII = 0.945 ± 0.003. The nuclear magnetic resonance of 39K has also been investigated at room temperature. The quadrupole parameters are e2qQ/h = 0.1032 ± 0.0004 MHz and η = 0.00. The quadrupole coupling tensors for 35Cl and 39K are compared with various model calculations. The temperature dependence of the quadrupole parameters for both Cl(I) and Cl (II) can be explained by introducing a single molecular torsional motion of the rigid (CuCl4∙2H2O)2− anion. The torsional motion has an angular frequency of ~3 × 1012 rad/s around the Cu—Cl(I) bond axis. This low frequency vibration might also be involved with the anomalous temperature dependence of Cu2+ electron spin resonance previously observed in this salt.
Low Angular Momentum States Populated in the Decay of 178Lu
Authors: Gujrathi S. C. , D'Auria J. M.
Published: April 2011

The low angular momentum states in 178Hf populated in the beta decay of the low spin state (T1/2 = 30 min) of 178Lu are investigated with both high resolution and high efficiency Ge(Li) detectors as well as a NaI(Tl)–Ge(Li) (γ,γ) coincidence system. The sources of 178Lu were produced through the 178Hf(n,p) and 181Ta(n,α) reactions on natural targets of hafnium and tantalum, respectively, using 14.8 MeV neutrons. Sixteen gamma transitions in the energy range 1090.8 to 1730.0 keV have been found to decay with the 30 min period of 178Lu. A decay scheme of 178Lu has been proposed with the excited levels in 178Hf at 93.17(2+), 306.59(4+), 1309.7(0+, 1±), 1362.7(0+, 1±, 2+), 1434.2(0+), 1442.9(0+), 1496.7(2+), 1514.2(2+), 1562.0(2+), 1772.1(0+, 1±, 2+), and 1823.2(0+, 1±, 2+) keV. The weak β-branching ratios and their log ft values are deduced from the observed γ-ray intensities and results thus obtained are discussed.
Temperature Variation of the Frequency of Longitudinal Inter-Planar Oscillations in Pyrolitic Graphite
Authors: Roy A. P.
Published: April 2011

The zone-boundary longitudinal phonon frequency, propagating along the hexad axis in pyrolitic graphite, has been measured by neutron spectrometry over a temperature range of 200 to 900 °K. The relative frequency change for this temperature interval, Δν/ν, is 0.07, a very high value in view of the lower limit for the melting temperature for graphite of 3800 °K.
N Mixing in the 2s-1d Shell
Authors: Hird B.
Published: April 2011

It is shown that the hexadecapole term as suggested by Turner and Trainor does not give [Formula: see text] for the ground state spin of 25Al and 25Mg when major shell mixing is taken into account. The effect of N mixing in the spheroidal core Nilsson model is examined, both with and without band mixing in the 2s-1d shell.
Gamma-Ray Linear Polarization and Angular Distribution Formulas in Terms of Phase-Defined Reduced Matrix Elements
Authors: Taras P.
Published: April 2011

Gamma-ray linear polarization and angular distribution formulas are presented in terms of the phase-defined reduced matrix elements of Rose and Brink. In particular, the mixing ratios are phase consistently related to reduced matrix elements of interaction multipole operators which are also well defined in phase. The mixing ratios extracted from the measurements of gamma-ray angular distribution and linear polarization can then be compared in both magnitude and sign with the predictions of nuclear models. The full potential of a gamma-ray linear polarization measurement is demonstrated by the discussion of a recent measurement.
Concerning a Possible K = 7/2 Negative Parity Band in 29Si
Authors: Spear R. H. , Cairns J. E. , Elliott R. V. , Kuehner J. A. , Pilt A. A.
Published: April 2011

Linear polarization studies of gamma radiation from the reaction 26Mg(α,nγ)29Si show that the parity of the 3.623 MeV [Formula: see text] state is negative, and that the spin and parity of the 5.255 MeV state are [Formula: see text] or [Formula: see text]. A previously reported unique [Formula: see text] assignment for the latter state is not confirmed.
Diffusional Pressure Narrowing in Induced Infrared Spectra
Authors: Zaidi H. R. , Kranendonk J. Van
Published: April 2011

The newly discovered pressure narrowing in quadrupole-induced infrared spectra is interpreted as due to diffusion. The effect makes possible the measurement of the diffusion constants in pure H2 and H2 – foreign gas mixtures at high densities by means of infrared absorption.
Studies of the Ionic Ferromagnet (LaPb)MnO3. VI. Antiresonance and the Ferromagnetic Resonance Line Shape
Authors: Wang S. T. , Searle C. W.
Published: April 2011

The resonance line shape and line width of the family La(1−x)PbxMnO3 have been examined from 77 to 430 °K in a frequency range from 13 to 25 GHz. The distorted line shape is in qualitative agreement with a calculation that includes the effect of the skin depth. The antiresonance condition has been observed and it is also in qualitative agreement with theory.
Spectrum of Br V
Authors: Budhiraja Charan J. , Joshi Y. N.
Published: April 2011

The spectrum of Br V has been revised and extended using an electrodeless discharge source. Twelve new lines have been assigned to the spectrum. A tentative value of the ionization potential has been found to be 502 860 cm−1 (62.33 eV).
Monte-Carlo Calculation of Antiprotons Annihilating (at rest) in Nuclei, Using the Isobar Model
Authors: Mes Hans , Hébert Jacques
Published: April 2011

A Monte-Carlo calculation has been used to simulate antiprotons annihilating (at rest) with the nuclei of the emulsion. Assuming that the final product of the annihilation is pions, the latter can interact with the nucleons to form isobars. The fate of these isobars inside the nucleus determines the ratio of absorbed to scattered pions. Two distinct cases are considered.
Analysis of the Excitation of the Earth–Ionosphere Waveguide by a Satellite-Borne Antenna
Authors: Einaudi F. , Wait J. R.
Published: April 2011

An analytical approach is outlined to obtain the fields near the earth's surface for a long wave transmitting antenna on a satellite. The medium is divided into slabs, each of which is characterized by a dielectric tensor. To simplify the calculations, a planar model is considered in which the d.c. magnetic field is vertical. An explicit derivation is given for a three-layer planar model: the lowest layer, up to ca. 70 km, represents the earth–ionosphere waveguide, the second layer may represent the D region; and the third layer is the one containing the satellite, which is idealized by a vertical electric dipole. Emphasis is placed on the relative launching efficiency of a satellite-borne antenna as compared with a ground-based antenna of the same strength. For sake of simplicity the antenna is idealized as an electric dipole and all sheath effects are neglected.
Dilatometric Study of the Crystallization Behavior of Pure and Doped Selenium
Authors: Janjua M. B. I. , Toguri J. M. , Cooper W. Charles
Published: April 2011

The crystallization behavior of pure vitreous selenium and selenium doped with various concentrations of arsenic, chlorine, bromine, and iodine was investigated by a dilatometric method, with particular emphasis on constancy of the thermal pretreatment of samples. The energy of activation for the crystallization of vitreous selenium was found to be 25 kcal/mole. Arsenic had a very pronounced retarding effect at the 100 ppm level. Chlorine and iodine showed a complex behavior, whereas bromine showed a moderate accelerating effect on the rate of crystallization of selenium.
Atomic Charge State Ratios of 6Li Ions from 5.8–16.4 MeV
Authors: Stocker H. , Berkowitz E. H.
Published: April 2011

The ratio, F2∞/F3∞, of equilibrium charge state fractions has been measured for 6Li2+,3+ ions in thin carbon foils and found to vary from 14%–1% over the ion energy range from 5.87–16.45 MeV. The measured ratio varies inversely with the fifth power of the ion velocity.
The Determination of the Polarization of 3He by Optical Methods
Authors: Daniels J. M. , Timsit R. S.
Published: April 2011

Two methods are described for determining the polarization of 23S13He by measuring the transmission of a test beam through the polarized gas. Satisfactory agreement was obtained between the polarizations measured by these methods, and a new formula for the determination of the polarization of 3He from the intensity of the scattered pumping light. This new formula takes into account the fact that the pumping light is not all parallel to the magnetic field, and that it may not be accurately circularly polarized.
The Polarizations Produced, and the Rates of Polarization, in the Optical Pumping of 23S13He
Authors: Timsit R. S. , Daniels J. M.
Published: April 2011

The optical pumping of metastable 3He atoms with circularly polarized resonance radiation from a 4He light source has been carried out at several 3He gas pressures and at different pumping light intensities and metastable atom concentrations. The dependence of both the equilibrium nuclear polarization and the pumping time on both the metastable atom density and the intensity of the pumping radiation is in satisfactory agreement with the theoretical predictions of Daniels and Timsit.
Emission of Neutrons from Muonic Lead and Bismuth
Authors: Srinivasan V. , Sundaresan M. K.
Published: April 2011

The emission of prompt neutrons from muonic bismuth observed experimentally is believed to be caused by the radiationless excitation of the target nucleus above the neutron separation energy by muonic transitions of the type np → 1s[Formula: see text]. The work of Zaretskii and Novikov for muon induced fission in uranium is extended to the case of muonic lead and bismuth. The ratio of rates of radiationless excitation to the radiative transition probabilities is calculated by the surface current model of Sliv to check a random phase approximation used in the calculation by Zaretskii. The neutron spectrum obtained using this nuclear branching in the cascade calculation is given for lead and bismuth.
The 235U − 207Pb and 238U − 206Pb Mass Differences
Authors: Kerr Donald P. , Bainbridge Kenneth T.
Published: April 2011

The Harvard University mass spectrometer with the lock-in amplifier method of peak matching has been used to measure the mass differences 235U − 206PbC2H5, 238U − 206Pb32S, 238U − 235U, and 206PbH − 207Pb. The mass differences 235U − 207Pb and 238U − 206Pb derived from the data are compared with the values obtained using the total energies released in the respective decay series.
On b.c.c. 3He, a Highly Anharmonic Crystal
Authors: Glyde H. R.
Published: April 2011

The self consistent (SC) theory of lattice dynamics for highly anharmonic crystals is derived via expansion and selected re-summation of the one phonon Green function. Since perturbation treatments of weakly anharmonic crystals use the same expansion, the two cases can then be viewed as variations in a single method. The SC theory to lowest (SCH) and second (SC2) order and a re-order potential power series in which each coefficient appears averaged over the vibrational motion is derived.The SCH theory with the leading correction in the new series, the cubic anharmonic term, is applied to b.c.c. 3He. Phonon frequency dispersion curves, lifetimes, sound velocities, and elastic constants are computed. The phonons are well defined and the elastic constants and isotropy agree quite well with experiment. Although the cubic correction is significant, it suggests that the re-ordered series converges.
On the Theory of Collision-Induced Absorption in Rare Gas Mixtures
Authors: Brenner S. L. , McQuarrie D. A.
Published: April 2011

The observed far-infrared collision-induced absorption of helium–argon mixtures is used to determine the parameters in an induced-dipole moment function of the form[Formula: see text]It is shown that, with this form of μ(r), the values of the constants μo, ρ, and c7 that are necessary to fit the first two moments of the observed absorption contour are in disagreement with the available theoretical values of these constants. Possible explanations for this disagreement are discussed in the paper. Finally, it is shown that if μ(r) were known, it is possible to obtain an excellent representation of the entire absorption spectrum from a knowledge of only the first three moments, which are easily calculated equilibrium quantities.
New Fits to the and Lee–Sugawara Relations
Authors: Yakimiw E.
Published: April 2011

We find that the [Formula: see text] sum rule for the nonleptonic Σ decay amplitudes is well satisfied when using the newly reported values of the Σ− decay rate and the Σ0+ asymmetry parameters. Moreover, the mild disagreement which has existed since 1964 with the Lee–Sugawara relation is shown to disappear when the latest data are used. The γ > 0 solution of the Σ0+ decay seems to be favored.
A Digital Mass Spectrometer
Authors: Cumming G. L. , Burke M. D. , Tsong F. , McCullough H.
Published: April 2011

A mass spectrometer control and recording system has been built which utilizes synchronous incremental stepping of the magnet current during the scanning of the mass spectrum with time-locked digitizing of the output, producing successive scans as similar time series and preserving the frequency spectral content of each scan. The digital output is recorded on magnetic tape and processed later on a computer. A new method of fitting polynomials to the reduced peak heights is described, which yields a measuring precision of about 0.06% at one standard deviation on 10–20 scans of the spectrum.Some studies of fractionation are described which illustrate the large errors which may occur from this effect.
Lifetime of the 3.163 MeV Level of 35Cl
Authors: Barton R. D. , Wadden J. S. , Carter A. L. , Pai H. L.
Published: April 2011

The lifetime of the 3.163 MeV level of 35Cl has been measured by an improved delayed coincidence technique. The mean lifetime was found to be (37 ± 4) ps.
On a Symmetry Property of the Inelastic Scattering Amplitude in the Adiabatic Approximation
Authors: Sherif H.
Published: April 2011

A symmetry property of the exact T matrix for the inelastic scattering of particles with arbitrary spin is derived, in the adiabatic limit, using time reversal invariance properties of the elastic scattering amplitude and neglecting interaction terms that involve spins or velocities of the target nucleons. The symmetry property is used to show the equality of the generalized polarization and asymmetry tensors for inelastic scattering and to derive the symmetry properties, with respect to the adiabatic recoil axis, of the angular correlation function and the circular polarization of the deexcitation gamma rays. It is also shown that the nuclear excited state is aligned along the axis normal to the scattering plane. A brief discussion of the symmetry properties of the adiabatic DWBA amplitude is given. When interaction terms involving spins or velocities of the target nucleons are taken into account, it is shown that the inelastic scattering T matrix can be divided into two parts; one that satisfies the above-mentioned symmetry relation, and a second part which has a different symmetry.
Propagation of VLF Waves below Generally Anisotropic Ionospheres
Authors: Abbas M. M. , Pidwell D. W. , Walsh E. J.
Published: April 2011

The coupled vacuum mode theory of Poeverlein is applied to the problem of VLF propagation in the Earth–ionosphere wave-guide. The curvature effects of the earth are included by assuming a cylindrically stratified medium. The modifications for cylindrical stratifications are introduced in the coupled vacuum mode equations through a conformal transformation. In this transformation, the field equations are converted from a cylindrical coordinate system into a Cartesian coordinate system. A solution of the coupled vacuum mode equations by numerical methods leads to the reflection coefficient matrix of the ionosphere for arbitrary directions of propagation and the magnetic field, and for arbitrary profiles of electron density and collision frequency.The reflection coefficient matrix for stratified and generally anisotropic ionosphere is employed in solving the modal equation for the Earth–ionosphere wave-guide. The reflection coefficient matrix for the ground is evaluated from formulas in which curvature effects of the Earth are included approximately. The modal equation is solved by an iteration procedure, and the propagation characteristics of the Earth–ionosphere wave-guide are calculated under a variety of ionospheric conditions. The variations of propagation characteristics are calculated as a function of frequency, the direction of propagation, and the dip angle of the magnetic field. A comparison of the numerical values with results of different formulations published in the literature indicates a fairly good agreement.
Lifetime of the 6s7p1P1 Level of Barium
Authors: Dickie L. O. , Kelly F. M.
Published: April 2011

The lifetime of the second excited singlet P level of barium 6s7p1P1 has been determined from the width of the Hanle resonance of the 6s7p1P1–6s21S0 3071.58 Å resonance line. The lifetime is determined to be 13.2 ± 0.4 × 10−9 s. From this lifetime the oscillator strength of the 3072 Å transition is 0.12 ± 0.05 and that of the 6s7p1P1–6s5d1D2 4726 Å is 0.09 ± 0.04.
Optical Constants of Sputtered Ferrite Films
Authors: Westwood W. D. , Sadler A. G.
Published: April 2011

Transmission and reflection spectra in the 250–50 000 cm−1 region have been obtained for nickel and cobalt ferrite films deposited by d.c. sputtering of the polycrystalline ferrites onto glass and fused-silica substrates. Both types of films exhibit an absorption edge at 14 000 cm−1.From interference effects in the films, dispersion curves have been obtained in the 4000–16 000 cm−1 range by a method which compensates for the absorption effects. In this region, the absorption coefficients were obtained from the dispersion curves and the transmission spectra. The results indicate that the films may be inhomogeneous. The refractive indices of nickel ferrite films 1000 and 23 600 Å thick are 2.7 and 2.1 respectively. A method for determining the optical constants from the reflectance and transmittance at higher frequencies was also investigated.
A Possible Test of the Validity of Time Reversal
Authors: Logan B. A.
Published: April 2011

A possible test of the validity of symmetry under time reversal is discussed. It is proposed to investigate time reversal by measuring any imaginary component of the mixing ratio in the mixed dipole–quadrupole transitions between nuclear levels. The experimental method is based on measurements of the angular correlation of a cascade from a level which is oriented by the inelastic scattering of polarized protons. The method is capable of improving on the accuracy of previous investigations.
Nuclear Absorption of Low-Energy Pions
Authors: Beder Douglas S.
Published: April 2011

We derive an expression for the mean free path of low energy π's traversing nuclear matter, assuming that absorption is dominantly on nucleon pairs. Relating the absorption cross section to the data for the inverse reaction NN → NNπ makes this susceptible to numerical calculation. We also discuss how properly to account for nucleon Fermi motion in calculating the absorption rate.
Depth Distribution of Implanted Oxygen in Gallium Phosphide Measured by Nuclear Reaction Techniques
Authors: Whitton J. L. , Mitchell I. V. , Winterbon K. B.
Published: April 2011

The depth distribution of ion implanted 18O in gallium phosphide has been measured by use of the nuclear reaction 18O(p,α)15N which has a sharp resonance at a proton energy of 639 keV. Implantation energies of 20, 40, and 60 keV were used and average concentrations were achieved of as high as 3 × 1021 ions/cm3 over the implanted depths. Post-annealing of the 20 keV implant at 600 °C caused a slight broadening of the distribution.A mathematical treatment is given whereby the 18O depth distribution can be derived from the experimental observation of the α-particle counting rate as a function of proton energy. This treatment involves a novel method of obtaining a smooth fit for the depth profile.Comparison of the smoothed experimentally measured distribution profiles with theoretical range distributions shows a reasonable fit, indicating that the projected ranges and distributions of oxygen implanted into GaP may be calculated with a fair degree of accuracy.