bluuebunny/crossref_metadata_2025 huggingface dataset:
ULTRAVIOLET ABSORPTION SPECTRA OF HCN AND DCN: I. THE α—X AND β—X SYSTEMS
Authors: Herzberg G. , Innes K. K.
Published: April 2011

The ultraviolet absorption spectra of HCN and DCN have been investigated below 2000 Å. Four band systems have been found of which two, α—X and β—X, are described and analyzed in the present paper. At the long wavelength end the α—X system in both HCN and DCN consists of simple progressions of sharp bands whose fine structure has been measured. At shorter wavelengths diffuseness (predissociation) sets in gradually but at somewhat different energies in HCN and DCN. Both the vibrational and rotational analyses lead independently and unambiguously to the conclusion that in the upper state, α, unlike in the ground state, the molecule is non-linear. The geometrical parameters obtained from the rotational fine structure are r0(CH) = 1.140 Å, r0(CN) = 1.297 Å, and [Formula: see text]H—C—N = 125.0°. Two vibrational frequencies in the α state are established: for HCN, ν1 = 1506, ν2 = 949; for DCN, ν1 = 1506, ν2 = 735 cm−1. The CH stretching frequency has not been found.The β—X system has been clearly observed only for DCN. In HCN it is apparently so strongly predissociated that its presence among the diffuse α—X bands is difficult to establish. In the β state, as in the α state, the molecule is bent. The somewhat fragmentary rotational analysis leads to r0(CN) = 1.334 Å and [Formula: see text]D—C—N = 114.5° when r0(CD) = 1.140 Å is assumed. Only one vibrational frequency, ν2 = 731 cm−1, has been established in the β state of DCN. The vibrational quantum number v2 is uncertain since no isotope effect is available to establish the position of the 0–0 band.In the rotational analysis, particularly of the α—X system, the effects of the asymmetry of the molecule in the upper state are clearly demonstrated by the doubling of the levels with K = 1 and K = 2 and the large contributions of the asymmetry to the terms in J2(J + 1)2. From the sign of the K-type doubling for K = 1 it follows unambiguously that both the α and the β state belong to the species A″, i.e. the electronic eigenfunctions are antisymmetric with respect to the plane of the molecule. It appears probable that both transitions α—X and β—X correspond to forbidden transitions (1Δ—1Σ+ and 1Σ−—1Σ+) of the linear case. The non-linear structure of the excited states is briefly discussed in terms of electron configurations.A number of interesting features of the predissociation in the α state are pointed out. It is shown that the dissociation products are in all probability H + CN(2Π).
ENERGY LEVELS OF SLIGHTLY ASYMMETRIC TOP MOLECULES
Authors: Polo S. R.
Published: April 2011

For the rotational analysis of the band spectra of slightly asymmetric tops it is convenient to have explicit expressions for the rotational energies in terms of the rotational quantum numbers. In the tables available at present the coefficients of the power series in the asymmetry parameter are only tabulated numerically for each individual rotational level. In the present work more general expressions are derived, giving the explicit dependence on J, K, and the asymmetry parameter ε (including terms up to ε5). First-order corrections for centrifugal distortion in terms of J, K, and ε have also been included.
DISCUSSION OF THE ELECTRICAL PROPERTIES OF COMPOUNDS WITH THE NICKEL ARSENIDE STRUCTURE
Authors: Pearson W. B.
Published: April 2011

A valence scheme has been proposed for alloys such as CrSe, MnTe, and FeS, with the nickel arsenide structure, which indicates why they may be semiconductors, while chalcogenides of Co and Ni and antimonides and bismuthides of Cr, Mn, Fe, Co, and Ni with a similar structure are metallic. The valence scheme is thus consistent with the known electrical properties (and also magnetic properties) of these phases. It then predicts that FeSe and CrS may well be semiconductors and indicates that all other compounds of Cr, Mn, Fe, Co, and Ni with the NiAs structure should be metallic.
THE EMISSION SPECTRUM OF THE PH+ MOLECULE
Authors: Narasimham N. A.
Published: April 2011

A system of three red degraded bands at 3854, 4228, and 3567 Å has been obtained in emission from a hollow cathode discharge through helium containing a little phosphorus vapor and hydrogen. Rotational analyses of the bands show that they are the 0–0, 0–1, and 1–0 bands of a 2Δ—2Π transition of the PH+ molecule. The 2Δ state is regular with small spin splitting (case b) while the 2Π state is regular with large spin splitting (case a). For ν = 0, the F1 levels of the 2Δ state with [Formula: see text] and the F2 levels with [Formula: see text] are predissociated. Also the lines arising from the F1 levels of the 2Δ state with ν = 1 are found to be extremely weak compared to those arising from the F2 levels. Vibrational and rotational constants have been determined and the dissociation energy has been found to be 3.06 ± 0.25 ev.
THE EMISSION SPECTRUM OF ALUMINUM MONOCHLORIDE IN THE VACUUM ULTRAVIOLET
Authors: Reddy S. Paddi , Rao P. Tiruvenganna
Published: April 2011

The spectrum of aluminum monochloride as excited in a high frequency discharge is photographed in the Schumann region using a 1 meter normal incidence grating spectrograph in the first order. Six brief new systems of bands were obtained in the region λλ2075–1820, in addition to three characteristic continua on the longer wavelength side of the discrete systems. The analyses of five of these systems indicate a common lower level which is identified as the ground state of the AlCl molecule. For the remaining system, only the upper state vibrational frequency ωe′ is derived. All these systems involve six new, hitherto unknown, excited electronic states of the AlCl molecule. The spectrum, when excited in a condensed discharge from a high voltage transformer through steaming AlCl3 vapor, is found to consist of numerous discrete emission bands in the region λλ2365–2020. These bands are different from those occurring in the high frequency discharge. Because of overcrowding of these bands, owing possibly to lack of adequate dispersion, no analysis is presented.
IONIZATION CURRENTS IN ARGON AND HELIUM LIQUIDS
Authors: Williams R. L. , Stacey F. D.
Published: April 2011

Ionization currents in alpha-irradiated argon and helium I and II liquids have been measured over an electric field range of 105:1, and conduction pulse amplitude distributions have been measured over a 300:1 range of applied field. A critical examination of theories of ionic recombination shows that they are unable to explain the results of the present experiment, and a new approach to the problem of columnar recombination is suggested.
THE CUMULATIVE YIELDS OF THE KRYPTON AND XENON ISOTOPES PRODUCED IN THE FAST NEUTRON FISSION OF Th232
Authors: Kennett T. J. , Thode H. G.
Published: April 2011

The relative fission yields for mass chains ending in stable krypton and xenon isotopes have been measured for the fast neutron-induced fission of Th232. Isotope dilution techniques were used to determine the krypton/xenon ratio to assist in obtaining the absolute fission yields for these mass chains. The absolute yields were determined by the use of two methods, both giving results which were in excellent agreement. The fine structure observed for the Th232 mass–yield curve is compared with that of heavier fissile nuclides.
A PROPOSED β-DECAY INTERACTION
Authors: Preston M. A.
Published: April 2011

It is shown that one can retain the two-component neutrino theory and time reversal with scalar and tensor interactions in the β-decay Hamiltonian, if one postulates that the scalar term produces neutrino emission and the tensor term antineutrino emission. This is consistent with all present experimental data.
A REVISED SEMIEMPIRICAL ATOMIC MASS FORMULA
Authors: Cameron A. G. W.
Published: April 2011

A new mass formula has been constructed which contains volume and surface energies, each with a symmetry energy contribution, Coulomb and Coulomb exchange energies, and shell correction and pairing energies. A nuclear model with a trapezoidal radial-density distribution was used. The central density was assumed constant, and the dimensions were adjusted to fit the Stanford electron-scattering results. The symmetry energy coefficients were determined by a least-squares fit to the valley of beta stability. The volume and surface energy coefficients were determined by a least-squares fit to 89 odd–odd masses uniformly spaced in mass number. The shell correction and pairing energies were assumed to be independent functions of the proton and neutron numbers; they were empirically determined from the differences between masses computed from the formula without corrections and those tabulated by Wapstra and Huizenga. The median energy difference between the corrected formula and the Wapstra–Huizenga masses is about 300 kev. Some remarks are made concerning the implication of these results for nuclear deformations and fission thresholds.
APPLICATION OF A COLLECTIVE MODEL TO Si29
Authors: Bromley D. A. , Gove H. E. , Litherland A. E.
Published: April 2011

A strong-coupling collective model has been applied to a description of the low levels of Si29. Detailed comparisons of the predictions of this model with static and dynamic properties of the low levels of the A = 29 isobaric system have been made; experimental data on the level spectrum, ground-state magnetic moment, decoupling parameter, reduced widths for nucleon capture in deuteron-induced stripping reactions, as well as gamma- and beta-ray transition widths have been used in the comparisons. These indicate that Si29 has an oblate shape with a spheroidicity parameter [Formula: see text]. Although agreement between experiment and theory is in some cases only qualitative, it is shown that current collective models have relevance for the description of nuclear properties in this mass range.
THE FREEZING POINTS OF HIGH PURITY METALS AS PRECISION TEMPERATURE STANDARDS: II. AN INVESTIGATION OF THE FREEZING TEMPERATURES OF ZINC, CADMIUM, AND TIN
Authors: McLaren E. H.
Published: April 2011

An investigation of freezing and melting temperatures with platinum resistance thermometry on high purity zinc, cadmium, and tin has been carried out. Using appropriate techniques, plateaus of essentially constant (< ±0.0001 °C.) temperature with durations of over 1 hour are readily obtained on the cooling curves of these metals. For series of freezes on particular samples, the standard deviations of the respective plateau temperatures were found to be of the order of ±0.0002 °C. It was not possible to distinguish among the plateau temperatures of three samples selected from different distillation batches of New Jersey S.P. zinc. Evidence is presented on the long term stability ([Formula: see text] years) of the plateau freezing temperature of S.P. zinc determined with six standard thermometers. The pressure effects on the freezing temperatures were found to be 0.0043 °C, 0.0062 °C, and 0.0033 °C. per atmosphere for zinc, cadmium, and tin respectively.Thermal analysis of these high purity metals reveals alloy structures and other features associated with nucleation, coring, and annealing phenomena; typical thermal curves are shown.
A METHOD FOR INTERPRETING THE DISPERSION CURVES OF WHISTLERS
Authors: Storey L. R. O.
Published: April 2011

This paper considers how the dispersion curves of whistlers may be interpreted to provide information on the distribution of electron density with height in the outer atmosphere.The simpler inverse problem, that of computing the dispersion curve for a given distribution, is considered first. On the assumption of longitudinal propagation in a dipole magnetic field, the dispersion curve is derived in the form of an equation relating the product [Formula: see text] to the frequency f. The equation can be represented by a power series in f, which is useful for estimating departures from the elementary [Formula: see text] relationship at frequencies where these departures are small. The coefficient of fn in this series is termed the ‘dispersion constant of order n’.The main problem is now treated, regarding the above equation as an integral equation determining the distribution of electron density along the path. This integral equation is solved in series, making use of the same power series in. The dispersion constant of order n is shown to be proportional to the nth moment of the distribution, suitably expressed and weighted. From the values of the moments it is possible to deduce both the initial geomagnetic latitude of the path and the distribution of electron density along it. When the observed dispersion curve is incomplete, so that only the dispersion constants of lower order can be measured, the method yields an approximation to the distribution.
CRITICAL STUDY OF VIBRONIC INTERACTION CALCULATIONS
Authors: Liehr Andrew D.
Published: April 2011

A detailed study of the published non-empirical and semiempirical calculations of vibronic (vibrational-electronic) interactions in the 1B1u and 1B2u states of benzene is carried out. It is found that, in all but the most detailed non-empirical theory of vibronic interactions (Liehr and Moffitt 1957a), the Goeppert-Mayer and Sklar (1938) benzene electronic wave functions are too crude to adequately describe such interactions. Also, it is shown that the previously proposed semi-empirical theories of vibronic interactions (Craig 1950; Liehr 1955; Liehr and Moffitt 1957b; Murrell and Pople 1956) are derivable from the more exact theory of Liehr and Moffitt (1957a) only with the aid of rather "herculean" assumptions.
THE DECAY OF Os185
Authors: Johns M. W. , Nablo S. V. , King W. J.
Published: April 2011

A study of the decay of Os185 with a magnetic beta-ray spectrometer, scintillation counters, and coincidence circuits reveals radiations of the following energies (in Mev.), intensities, and multipolarities: K-shell X-rays (65%), 0.0716 (0.4%, M1 + E2), 0.1255 (2.5%, M1 + E2), 0.1626 (1%, M1), 0.2334(1.4%, E2), 0.5920 (1.1%, E2), 0.6458(80%, E2), 0.7177 (4.1%, M1 + E2), 0.8720 (7.1%, M1 + E2), and 0.8789 (7.5%, M1 + E2). These transitions are interpreted in terms of a decay scheme involving the following levels in Re185: 0(5/2+), 0.1255(7/2+), 0.6458(1/2+), 0.7176(3/2+), 0.872(3/2+), and 0.879(3/2+) Mev.The ratio of L-capture to K-capture considering decay to all levels of Re185 is 0.38 ± 0.07. The ratio of L-capture to K-capture to the 0.872 and 0.879 Mev. levels is 1.04 ± 0.04. This implies that the Os185-Re186 atomic energy difference is 0.985 ± 0.007 Mev. The half-life of Os185 was found to be 93.6 ± 0.5 days.
METEOR SIGNAL RATES OBSERVED IN FORWARD-SCATTER
Authors: Vogan E. L. , Campbell L. L.
Published: April 2011

Diurnal and seasonal variations in meteor signal rate observed during a 15 month period over a forward-scatter path situated in eastern Canada are discussed. Measurements were made at a frequency of 49.98 Mc./s. The data show a large spread from hour to hour and day to day with the greatest signal rate being observed during the summer months. The influence of ionospheric absorption on the signal rate observed during the morning hours is considered and it is concluded that the presence of a small amount of attenuation can modify appreciably the form of the diurnal variation.
EVIDENCE FOR THE FORMATION OF LONG-LIVED Bi208 BY THE (n, 2n) REACTION ON BISMUTH
Authors: Roy J. C. , Eastwood T. A. , Hawkings R. C.
Published: April 2011

Long-lived Bi208 has been observed through its decay by electron capture to the first excited state of Pb208 at 2.61 Mev. It has been produced by the (n, 2n) reaction on Bi209 in the NRX reactor. The half-life of Bi208 has been estimated to be 3 × 104 years, with an uncertainty of a factor of about 2.
DIURNAL VARIATIONS IN THE NUMBER OF SHOWER METEORS DETECTED BY THE FORWARD-SCATTERING OF RADIO WAVES: PART III. ELLIPSOIDAL THEORY
Authors: Hines C. O.
Published: April 2011

A theory of meteor 'observability' relating to forward-scatter radio experiments was developed in Part I of this series, with the use of a simplifying 'cylindrical approximation'. The application of the theory to data obtained during meteor showers provides a promising new method for studying the intrinsic strengths of the showers. The principal limitation of the method is due to the inaccuracies of the cylindrical approximation. In the present paper, these inaccuracies are removed by a full development of the ellipsoidal geometry inherent in the forward-scatter process. The more rigorous results are compared with the approximate results at various stages throughout the analysis.
AN EXPERIMENTAL STUDY OF THE BAND INTENSITIES IN THE CN RED SYSTEM
Authors: Dixon R. N. , Nicholls R. W.
Published: April 2011

Experimental band intensities in the CN red system, A (2Πi) →X(2Σ+), have been measured using an active nitrogen – carbon tetrachloride source. Using calculated Franck–Condon factors qν′ν″ the electronic transition moment Re(r) is found to vary little over the range 1.04 < r < 1.27 Å.
ROTATIONAL SPECTRA OF RbF BY THE ELECTRIC RESONANCE METHOD
Authors: Lew H. , Morris D. , Geiger Jr. F. E. , Eisinger J. T.
Published: April 2011

Transitions between the J = 0 and J = 1 rotational states of RbF have been measured by means of the molecular beam electric resonance method. The following rotational constants have been determined (all frequencies in Mc./sec):[Formula: see text]The quadrupole interaction constants −eqQ/h in the J = 1 state are found to be[Formula: see text]The equilibrium internuclear distance is re = (2.26554 ± 0.00005) × 10−8 cm. The electric dipole moment of Rb85F in the ν = 0 state is μ = (8.80 ± 0.10) × 10−18 e.s.u. The mass ratio of the Rb isotopes is M85/M87 = 0.9770148 ± 0.0000052.
THE SELF-CONSISTENT FIELD WITH EXCHANGE FOR NEON BY FERUT PROGRAM
Authors: Worsley Beatrice H.
Published: April 2011

A general program for the computation of atomic self-consistent fields with exchange has been prepared for the University of Toronto electronic digital computer, FERUT. It was developed by application to neutral neon, for which the results are given, and tested against the independently calculated results for Fe+14 and Fe+16.
AN INTERPRETATION OF THE LOW-LYING EXCITED STATES OF Mg25 AND Al25
Authors: Litherland A. E. , McManus H. , Bromley D. A. , Gove H. E. , Paul E. B.
Published: April 2011

A description of the experimental results obtained for Mg25 and Al25 is given based upon the assumption that the excited nuclear states are rotational states. In Mg25 and Al25 members of four rotational bands can be identified. The band based on the ground state can be assigned K = 5/2 whilst the three excited-state bands, two positive parity and one negative parity, can be assigned K = 1/2. The dipole γ-ray transitions between the K = 1/2 bands and the ground state K = 5/2 band are forbidden on the rotational model and it is a salient feature of the γ-ray cascading in Mg25 and Al25 that the ground-state transitions are always amongst the weakest transitions from excited states assigned to K = 1/2 bands. Besides giving a quantitative account of the γ-ray decay of the excited states the rotational model also predicts the number and type of the bands observed. The experimental values of the Mg24(d, p)Mg25 deuteron stripping reduced widths can also be approximately predicted by the model.
FIELD OF A DIELECTRIC-LOADED, INFINITE CORNER REFLECTOR
Authors: Adey A. W.
Published: April 2011

A study has been made of the effect on the radiating properties of an infinite corner reflector of loading its apex with a section of a dielectric cylinder of polystyrene and of a material with a relative permittivity of 4. Calculations of the radiation resistance and of the far-field amplitude have shown them to be sensitive to the presence of the loading, particularly for small spacings of the feeding element from the apex.
SOME OBSERVATIONS OF GEOMAGNETIC MICROPULSATIONS
Authors: Duffus H. J. , Shand J. A.
Published: April 2011

New observations are reported of the diurnal variation, direction, frequency spectrum, and geographical distribution of geomagnetic micropulsations (Pc and Pt). It is argued from a comparison of published data that these phenomena have primarily a solar time dependence, and may occur locally. At our two stations, separated by 60 longitude degrees, related signals are only occasionally observed. The phase characteristics of such related signals, together with differences in directional characteristics reported by other observatories, put serious strain on recent theories of the outer atmospheric origin of micropulsations.
MAGNETORESISTANCE AND FIELD DEPENDENCE OF THE HALL EFFECT IN INDIUM ANTIMONIDE
Authors: Fischer Gaston , MacDonald D. K. C.
Published: April 2011

Magnetoresistance and Hall-effect measurements in InSb are described. This semiconductor has charge carriers with sufficiently long mean free paths, l, that it is possible, even at room temperature and with available magnetic fields, to obtain l/r values considerably greater than unity, r being the orbital radius of a charge carrier moving in the applied magnetic field. The classical two-band theory has been found to account rather well for the results up to the highest magnetic fields employed. A review of the underlying assumptions of this theory is presented, and simple formulae are derived which allow the concentrations and mobilities of both types of carriers to be calculated from the magnetic field dependence of the resistivity, ρH, and of the Hall-constant, AH. The parameter Λ ≡ [(AH−A0)/A0]/[(ρH−ρ0)/ρ0] provides a useful means to check the consistency of the theory and can give some indication of the variation of the mobilities with the magnetic field.
RADIOACTIVE ISOTOPES OF RHENIUM AND OSMIUM FORMED BY THE BOMBARDMENT OF RHENIUM WITH PROTONS
Authors: Foster J. S. , Yaffe L. , Hilborn J. W.
Published: April 2011

Targets of normal rhenium, and of rhenium enriched in each stable isotope, were bombarded by protons in the energy range 10 to 80 Mev. These produced osmium and rhenium isotopes of masses 185, 183, 182, 181, and 180. After chemical separations, the gamma rays and conversion electrons were examined for half-lives, and to determine certain conversion coefficients. Independent isomers of Os183 with 10 and 15.4 hour half-lives were found. Gamma rays with energies 168.1, 850, and 1097 kev. were assigned to the 10 hour isomer, and gamma rays with energies 114.6, 168.7, and 382.4 kev. were assigned to the 15.4 hour isomer. In addition, the half-lives of Os185, Os182, and Re183 were observed to be 93.4 days, 21.9 hours, and 67.6 days respectively. Activities with half-lives of 19 hours, 23 minutes, 18 minutes, and 2 minutes were tentatively assigned to Re181, Os181, Re180, and Os180 respectively.
A STUDY OF NUCLEON FORCES WITH REPULSIVE CORES: IV. CALCULATIONS OF THE SHAPE-DEPENDENT PARAMETERS IN NEUTRON–PROTON SCATTERING
Authors: Preston R. L. , Preston M. A.
Published: April 2011

The magnitudes of the coefficients P and Q in the phase-shift expansion k cot [Formula: see text] have been investigated in the case of repulsive-core NP interactions. For square, Gaussian, exponential, and Yukawa shapes, which fit experimental values of the scattering length and the effective range, the shape-dependent parameter P has been computed as a function of rc in both singlet and triplet states. Also, for square and Yukawa shapes, which fit the scattering length and effective range, Q has been computed in the singlet state.
THE SOMMERFELD MODEL AND THE HEAT OF SOLUTION OF AN ALLOY
Authors: Henry W. G.
Published: April 2011

An approximately self-consistent method, using a Sommerfeld model, and incorporating an approximation to the second-order perturbation energy (Lennard-Jones 1930), is used to calculate the heat of solution of both monovalent–monovalent and monovalent–polyvalent alloy systems. The heat of solution, as given by the second-order approximation, varies directly with the square of the perturbing potential, and inversely with the mean total energy of the free electrons in the solvent. Varley's (1954.) result resembles this, except that his expression varies inversely with the mean kinetic energy of the free electrons in the pure solute. The first-order approximation to the energy of the alloy system is identical, except for a change of sign, with the expression suggested by Friedel (1952, 1954) for the heat of solution. The charge accumulation about a solute site is found to vary directly with the strength of the perturbation, and inversely with the mean energy of the free electrons in the solvent. Varley obtained a comparable expression; however, his function varies inversely with the mean kinetic energy of the free electrons in the pure solute. The calculated charge accumulations in the copper–silver system, and for gold dissolved in silver, agree qualitatively with those of Arafa (1949) and Huang (1948).
AURORAL RADIATION AT 500 Mc.
Authors: Hartz T. R.
Published: April 2011

An observation of radio noise emissions at 500 Mc. from a type A red auroral display which occurred on October 21–22, 1957, is reported. The circumstances surrounding this phenomenon are considered, and the unusual display is linked to a large flare on the sun some 30 hours earlier. It is concluded that an unusually large particle flux for the ejected solar matter would produce sufficient ionization in local regions of the ionosphere so that auroral radio emissions would be possible.
LOW-FIELD MOBILITY OF CARRIERS IN NONDEGENERATE SEMICONDUCTORS
Authors: Sodha Mahendra Singh , Agrawal Desh Bandhu
Published: April 2011

Gunn's theory of the low-field variation of carrier mobility has been extended, using Morgan's analysis to include the effect of scattering by a single optical mode of lattice vibrations. Numerical results obtained for n-germanium show that there is still a serious disagreement between theory and experiment.
CALCULATION OF THE THERMAL CONDUCTIVITY OF POROUS MEDIA
Authors: Woodside William
Published: April 2011

The problem of determining the effective thermal conductivities of porous and other composite materials from the conductivities and volume fractious of their constituents is examined. An approximate equation is derived for the case of a cubic lattice of identical spherical particles in a medium having properties different from those of the particles. This equation is applied to the calculation of the thermal conductivity of snow at different densities in the range 0.10 to 0.48 gm/cc. The effect of water vapor diffusion in snow under a temperature gradient is taken into account by adding a latent heat term to the conductivity value for dry air. Conductivity values for snow, calculated in this manner, are found to agree satisfactorily with experimental data. An equation due to Russell is also shown to give conductivity values for several cellular thermal insulating materials which are in good agreement with experimental values.
THE VARIATION OF SEA LEVEL COSMIC RAY INTENSITY BETWEEN 1954 AND 1957
Authors: Fenton A. G. , Rose D. C. , Fenton K. B.
Published: April 2011

Results from neutron monitors and meson telescopes at Ottawa (geomagnetic latitude 57° N.) and Resolute (geomagnetic latitude 83° N.) are presented for the years 1954–57, a period of increasing solar activity. The results indicate that the sea level meson intensity at these latitudes decreased by 5–6% between April 1954 and December 1957. During the same period the intensity of the nucleonic component at these stations decreased by over 22%. Investigation of the relative response of the two types of recorder to transient decreases during this period indicates that the long term change in the intensity level cannot be explained completely as an accumulation of shorter transient decreases, which become more frequent at times of high solar activity. It is concluded that the transient decreases are superimposed upon the longer term changes, each being produced by a separate modulation process but ultimately controlled by the general level of solar activity. Significant differences are found in the shape of transient decreases observed at the Canadian stations, both between different components at the one station and the same component at different stations. These may be interpreted as due to a varying energy dependence from one transient decrease to another, and to anisotropy in the primary cosmic radiation at these times.
SOME OBSERVATIONS OF AURORA USING A LOW-POWER FREQUENCY-MODULATED RADAR
Authors: Collins C.
Published: April 2011

A frequency-modulated, continuous-wave radar seems to be particularly well suited to the observation of auroral ionization, since it provides both range information and a Doppler indication of radial motion. An experimental equipment of this type has been operated for a few months near Ottawa. The system parameters are briefly considered and the radar observations are compared with similar measurements made with higher-powered pulse systems.
THE THERMAL NEUTRON CAPTURE CROSS SECTION AND THE RESONANCE ABSORPTION INTEGRAL OF Th230 (IONIUM)
Authors: Cabell M. J.
Published: April 2011

The thermal neutron capture cross section and the resonance capture integral of Th230 have been determined by an activation method. Assumptions are made that the thermal capture cross section and the resonance capture integral of Co59 are 36.5 barns and 48.6 barns respectively, that the half-life of Th230 is 8.00 × 104 years, and that Th230 behaves as a 1/v absorber in the subcadmium region. Based on these assumptions values of σ2200 = 21.4 ± 0.3 barns and of 937 ± 32 barns for the resonance absorption integral (from 0.5 ev to ∞) have been obtained for Th230.The half-life of Th231 has been determined as 25.52 ± 0.01 hours.
NUCLEAR ORIENTATION EXPERIMENTS WITH Pr142 AND Yb175 NUCLEI
Authors: Daniels J. M. , Lamarche J. L. G. , Blanc M. A. R. Le
Published: April 2011

Pr142 has been oriented as an impurity in cerium magnesium nitrate, and the anisotropy of the 1.57 Mev γ-ray was measured as a function of temperature in the range 0.003° K to 1.0° K, both in zero external field and in a field of 320 gauss parallel to the trigonal crystal axis. The results are not consistent with what has been published about the spin Hamiltonian of Pr+++ in this lattice. The magnetic moment of Pr142 is very small, and it was not possible to see any saturation of the anisotropy at low temperatures. Values for the magnetic moment of Pr142 were found for two different assumed decay schemes, these are 0.11 nuclear magnetons for the spin assignments [Formula: see text], and 0.15 nuclear magnetons for the spin assignments [Formula: see text]. Similar experiments were carried out on Yb175. Measurements were made in a variety of external magnetic fields up to 700 oersted, and at temperatures as low as 0.003° K. No anisotropy was observed for the 396 kev γ-ray, nor for the 282 kev γ-ray. The most likely explanation for this result is that the lifetime of the γ-emitting state is about 10−10 seconds. The relation between the results of this experiment and others on the same isotope (Phil. Mag. 2, 1079 (1952)) is discussed.
THE NON-MARTENSITIC DIFFUSIONLESS TRANSITION IN MANGANESE ARSENIDE AT ABOUT 40 °C
Authors: Basinski Z. S. , Pearson W. B.
Published: April 2011

We have investigated the nature of the transition at about 40 °C in manganese arsenide. It is already well known that the transition involves a discontinuous change of the length of the a axis of the hexagonal unit cell, and that there is no change of crystal structure. The transition is accompanied by a loss of ferromagnetism of MnAs on proceeding to higher temperature. We find that the transformation takes place by a novel diffusionless non-martensitic mechanism. It appears that plastic deformation of MnAs is impossible and so, instead of the change following the martensitic pattern, the strain energy of the transformation is minimized by a fragmentation of the crystal grains into pencil-like subgrains whose direction lies parallel to the c axis of the crystals.
NUCLEAR LEVEL SPACINGS
Authors: Cameron A. G. W.
Published: April 2011

T. D. Newton's shell-dependent level spacing formula [Formula: see text] depends upon the densities of single-particle orbits near the Fermi level in the nucleon gas. It has been found that these densities can be computed by taking appropriate averages of the second differences between adjacent atomic masses, using the writer's semiempirical mass formula from which electrostatic and pairing energy terms have been omitted. With this procedure, observed nuclear level spacings have been fitted with a root mean square error factor of 1.74. This fit shows that the level spacings are proportional to (2J + 1)−1 to a good approximation. Since the average density of single-particle orbits depends on the nuclear excitation energy, and since its computation takes a long time even with an electronic computer, an approximation formula with five coefficients has been fitted to the computed orbit densities for each Z and N in the ranges [Formula: see text] and [Formula: see text]. These coefficients are tabulated.
MEASUREMENTS OF ABSOLUTE PAIR PRODUCTION CROSS SECTIONS AT LOW ENERGIES
Authors: Standil S. , Shkolnik V.
Published: April 2011

Using an improved analysis in conjunction with a relative method for the measurement of absolute pair production cross sections, the pair production cross sections per atom of lead have been measured for the gamma rays emitted by Co60 and Sb124. The Z-dependence of this cross section was measured for the Co60 radiation using targets of Al, Fe, Cu, Mo, Ag, Sn, and Pb. The results obtained are generally in agreement with other experimental determinations and are, along with those of other investigators, represented graphically.
STUDY OF Ir191m
Authors: Cloutier J. A. R. , Henrikson A.
Published: April 2011

Using the McGill 100-Mev proton synchro-cyclotron, the half-life of Ir191m has been redetermined and the value 4.53 ± 0.18 s obtained from 55 trials. The mass assignment is here based on the study of the excitation curves for both osmium and iridium targets. The measured αk = 2.0 ± 0.3 for the observed 126 ± 6 kev gamma ray is consistent with the M1 + E2 assignment previously made. No 42-kev gamma ray could be detected.
NOTE ON THE SINGLE-PARTICLE ENERGY AND THE BINDING ENERGY OF MANY-BODY, SATURATED SYSTEMS
Authors: Baker Jr. George A.
Published: April 2011

Brueckner has recently pointed out that, for saturation, (Eav−E(pF)) does not vanish in general because of "important many-body contributions to the single particle energy which arise from the effects of the exclusion principle and from the variation of the self-consistent excitation spectrum with density." It is the purpose of this note to evaluate this difference in terms of the properties of the single-particle potential.
CALCULATION OF FREQUENCIES AND RELATIVE INTENSITIES OF NUCLEAR SPIN RESONANCE LINES IN CRYSTALS
Authors: Bloom M. , Robinson L. B. , Volkoff G. M.
Published: April 2011

Previous calculations of the dependence on the strength of the external magnetic field H0 of the energy levels and the expected frequencies of nuclear spin resonance lines of Al27 nuclei in a single crystal of LiAl(SiO3)2 (spodumene) have been extended over a wide range of H0 to more general orientations of the crystal with respect to H0.In order to describe the variation with H0 of the relative signal strength of a nuclear spin resonance line in a crystal, as observed with a crossed-coil spectrometer, a system of modified Bloch equations has been set up which describe the behavior of the magnetization vector of a two-level system when transitions are induced by an oscillating magnetic field. Solutions of these equations are used to explain the difference in the dependence on H0 of signal strengths in crossed-coil and in single-coil spectrometers.
ON THE RATE OF CONVERGENCE OF THE SPHERICAL-HARMONICS METHOD IN THE MILNE PROBLEM
Authors: Davison B.
Published: April 2011

The extrapolated end point, z0, and the ratio of current to flux at the free surface, j(0)/ρ(0), for the Milne problem are evaluated by the spherical-harmonics method in the PN approximation, N being odd. It is shown that, for N large, the approximations to these quantities are related to the exact values by[Formula: see text]in which c is the number of secondaries per collision, f1(c) and f3(c) are independent of N, and ζ1 and ζ2 are the absolutely lesser and greater roots of[Formula: see text]κ being the exact inverse diffusion length. The relation (A) is subject to the restrictions[Formula: see text]
ACTIVATION ENERGY FOR CREEP OF TIN
Authors: Bonar L. G. , Craig G. B.
Published: April 2011

The literature reports values ranging from 8000 to 26,000 cal per g-atom for the activation energy for the creep of tin. The present investigation analyzed the results of constant stress creep tests during steady state creep, and by means of temperature cycling. A value of approximately 9000 cal per g-atom for the creep of high purity tin in the temperature range 300 to 350° K was obtained.
ASYMMETRY OF THE CONCENTRATION FRONT DURING MISCIBLE DISPLACEMENT IN POROUS MEDIA
Authors: Scheidegger A. E. , Larson V. C.
Published: April 2011

During many feasible experiments concerning miscible displacement in porous media, it has been noted that the concentration front is slightly asymmetric. It is possible that this is due to an asymmetry in the boundary conditions which is present in most practicable displacement experiments. The present paper endeavors to investigate the influence of asymmetric boundary conditions upon the shape of the concentration front: The diffusivity equation basic to the theory of miscible displacement has been solved for the case of injection of fluid of constant concentration at one end of a long, linear porous medium. The solution has been effected by an electrical analogue computer. Curves showing the asymmetry are given.
ROTATIONAL ANALYSIS OF THE γ SYSTEM OF THE PO MOLECULE
Authors: Rao K. Suryanarayana
Published: April 2011

The bands of the γ system of the PO molecule have been photographed under high dispersion (0.35 Å/mm). A rotational analysis of the 0–0, 0–1, and 1–0 bands is given, which differs from the one previously given by Sen Gupta. In addition, four more bands, namely, the 1–2, 2–1, 2–3, and 2–4 bands, have been analyzed. The bands are attributed to the electronic transition, A3Σ–X2Πreg, the lower state being the ground state of the molecule. The new rotational constants for the ground state are the following:[Formula: see text]The spin doubling in the upper state is small. Perturbations in the v = 0 level of the upper state, which were not reported previously, are observed and discussed. They supply a welcome confirmation of the correctness of the analysis here presented.
POLARIZATION FLUCTUATIONS IN A FERROELECTRIC CRYSTAL
Authors: Burgess R. E.
Published: April 2011

The theory of thermal fluctuations of electrical polarization in a ferroelectric crystal is considered with special attention to temperatures in the neighborhood of the Curie point. Models giving a second-order transition are discussed thermo-dynamically, and the free energy with its derivatives yield the mean value and variance of dipole moment. The fluctuations and their spectral density are related respectively to the real and imaginary parts of the susceptibility of the crystal in conformity with Nyquist's theorem, which is not violated by the presence of a constant applied electric field. The g–r. theorem is shown to be applicable to equilibrium and non-equilibrium conditions, and its extension to lambda-point phenomena generally is discussed.
THE RESOLUTION CORRECTION IN THE SCINTILLATION SPECTROMETRY OF CONTINUOUS X RAYS
Authors: Dixon W. R. , Aitken J. H.
Published: April 2011

The problem of making resolution corrections in the scintillation spectrometry of continuous X rays is discussed. Analytical solutions are given to the integral equation which describes the effect of the statistical spread in pulse height. The practical necessity of making some kind of numerical analysis is pointed out. Difficulties with numerical methods arise from the fact that the observed pulse-height distribution cannot be defined precisely. As a result it is possible in practice only to find smooth "solutions". Additional difficulties arise if the numerical method is based on an invalid analytical procedure. For example matrix inversion is of doubtful value in making the resolution correction because there does not appear to be an inverse kernel for the integral equation in question.
A PHENOMENOLOGICAL THEORY OF INDUCED ELECTRICAL POLARIZATION
Authors: Wait James R.
Published: April 2011

A brief theoretical derivation is presented for the effective conductivity and dielectric constant of a homogeneous medium loaded with a uniform distribution of spherical conducting particles. To account for the effect of induced polarization, the particles are taken to have a concentric membrane or film which has a blocking action to the current flow into the particle. The characteristics of this phenomenological model are very similar to the experimentally observed features of induced polarization in a block of compacted andesite particles which contains a dissemination of small metal particles and is partially saturated with a weak electrolyte.The theory is then extended to a two-layer medium where the lower region is polarizable. The results explain, at least in a qualitative way, the observed features of induced electrical polarization in rocks, soils, and clay.
A MICROWAVE ANTENNA WITH RAPID SAW-TOOTH SCAN
Authors: Foster J. S.
Published: April 2011

In one of many forms of this device, a parallel beam of microwave radiation, originating within the rotor, passes between coaxial rotor and stator conical conducting surfaces. The successive wave fronts consequently show a uniform rotation about a fixed stator barrier. This barrier removes the radiation which is subsequently directed to the linear focus of a parabolic cylinder serving as the antenna. The resulting rapid saw-tooth scan covers a range nearly equal to π times the total conical angle. The chief advantages of this system are (1) high speed of scan, (2) time between successive signals from any object is constant, (3) insensitivity to changes in magnetron frequency, (4) beam of constant form and intensity, (5) occurrence of the scanning at the exit barrier only, hence there is no side slap inside the conical structure, (6) relatively high efficiency.The beam must be properly directed through the conical structure. Scanners cannot be placed in tandem to get multiple angular ranges. A simple scanner is limited to a range of about 45°, but a more complex system is described which will cover 80°.
NUMERICAL DETERMINATION OF THE FACTOR OF ENCIRCLED ENERGY RELATIVE TO A DIFFRACTION PATTERN OF REVOLUTION
Authors: Lansraux Guy , Boivin Germain
Published: April 2011

An optical system which is symmetrical about some axis forms a diffraction pattern around its focus F in an observation plane II.The factor of encircled energy E(W) is, apart from a normalization factor, the energy spread over the II plane inside a circle of radius W, centered on F.Although it is a good test for the quality of an optical system, the factor of encircled energy has not been used a great deal because of the lengthy calculations that its numerical determination requires. Two rapid computing methods are exposed here, with tables allowing a complete determination of E(W).
ATMOSPHERIC EFFECTS ON COSMIC RAY INTENSITY AT SEA LEVEL
Authors: Mathews P. M.
Published: April 2011

Cosmic ray intensity variations of primary origin and those caused by meteorological changes appear superposed in records obtained from meson counter telescopes and neutron monitors at sea level. The study of either of these types of variation is thus greatly complicated by the presence of the other. In the present work, we have for the first time taken the step of processing the raw data to eliminate primary variations (and the inherent statistical fluctuations) so as to make possible a direct comparison of the remaining variations with the changes in atmospheric variables over the same period. The subsequent analysis confirms the expectation that there are no appreciable atmospheric effects on the intensity of the nucleonic component beyond the well-known effect associated with the sea level barometric pressure B. But in the meson case there is strong evidence that the widely used set of variables H100, T100 (the height and temperature of the 100-mb level) and B is not very suitable for representing atmospheric effects; it seems essential to include a variable representing temperatures in the lower part of the atmosphere, and the set of variables T800 (temperature of the 800-mb layer), H100, and B, with coefficients kT = −.082 ±.008%/°C, kH = −3.04 ±.61%/km, and kB = −.134 ±.004%/mb appears to be the best. The theoretical formula of Dorman (1957), with a barometric coefficient β = −.147 ±.004%/mb and with the term representing the "temperature effect" reduced by a factor.76 ± .03, gives slightly better results. However, the improvement, at least in the case of the data we have analyzed, is too small to justify the great labor involved in using this formula.
FLUCTUATIONS IN THE INTERMEDIATE STATE OF SUPERCONDUCTING TANTALUM
Authors: Baird D. C.
Published: April 2011

Current noise in the intermediate state of superconducting tantalum has been studied by using continuous recording of the potential across a wire carrying a current greater than the critical. The pattern of the noise fluctuations becomes clarified by the use of short specimens showing the noise to arise from spontaneous transitions between discrete resistance levels. The nature of these levels is described and their existence attributed to an intermediate state structure which is not small in scale compared with the specimen dimensions. The dependence of the resistance level scheme on the sample demonstrates the importance of the influence of the lattice structure.
RADIATION AND RECEPTION PROPERTIES OF A WIDE SLOT IN A PARALLEL-PLATE TRANSMISSION LINE: I
Authors: Millar R. F.
Published: April 2011

A solution is obtained to the problem of radiation from a slot in a parallel-plate transmission line when excited by an E-polarized, dominant mode wave. Expressions are obtained for the reflection and transmission coefficients, and the polar diagram of the radiated field. Explicit calculations are performed when the width of the slot is much greater than the free-space wavelength of the incident radiation.An application of the Lorentz reciprocity theorem yields, without further analysis, the amplitude and phase of the propagated wave which is excited in the line by an incident cylindrical or plane wave.
IONIZATION LOSS BY COSMIC-RAY MU-MESONS IN ARGON
Authors: Hall Georges
Published: April 2011

The ionization of argon by cosmic-ray mu-mesons of minimum specific ionization has been studied by means of a calibrated pressure-ionization chamber using electron collection. Corrections which are shown to be necessary have been applied to the experimental data. The shape of the experimental curve of statistical distribution of energy loss agrees with the theoretically predicted shape, for energy losses greater than the most probable loss (300 kev).
THE THEORY OF THE PHOTONUCLEAR REACTION USING THE INDEPENDENT PARTICLE MODEL OF THE NUCLEUS
Authors: Sueoka Seiichi
Published: April 2011

For high-energy photonuclear reactions, particularly for the direct emission of a neutron, the integration of the matrix element of the interaction energy of the nucleus and the radiation field is carried out without the usual expansion in a series of multipoles. The method is applied to the O16, O17 nuclei, with harmonic oscillator wave functions for the nucleus. The ratio of the cross section obtained by the present method and that by considering only dipole absorption is found for various γ-ray energies.