bluuebunny/crossref_metadata_2025 huggingface dataset:
THE FLASH PHOTOLYSIS OF DIACETYLENE
Authors: Callomon J. H. , Ramsay D. A.
Published: April 2011

A brief description is given of a "microsecond" flash photolysis apparatus in which a 40 µf. condenser charged to 8000 v. is discharged through a photolysis flash tube in ~20 microseconds. Absorption spectra of transient species are photographed with a second flash tube which provides a source of continuum by discharging a 2 µf. condenser charged to 10,000 v., in 3–5 microseconds. A circuit for controlling the time interval between the two flashes is given.Experiments on the flash photolysis of diacetylene are discussed. With diacetylene at 0.5 mm. Hg pressure several well-known band systems were photographed in absorption 20 microseconds after the beginning of the photolysis flash, viz., the C2 Swan bands, the C2 Phillips bands, the C2 Deslandres–d'Azambuja bands, the 4050 Å bands of C3, and the CH band at 3143 Å. The rotational temperature of these bands was ~3000°–5000° K. The C2 Swan bands were also recorded in emission after a single photolysis flash. When a considerable excess (100:1) of helium was added to the diacetylene, all the above band systems disappeared with the exception of the C3 bands.In the absence of helium it is probable that the reaction is mainly thermal and that the high temperature is produced by a thermal explosion of the diacetylene triggered by the photolysis flash. The thermal reaction is suppressed by the addition of excess helium and the photochemical reaction becomes dominant. Under these conditions it is interesting to note that C3, but no C2, is produced. It appears therefore that C3 is a product of the photochemical decomposition of diacetylene. Possible mechanisms are discussed.
THE NEUTRON CAPTURE CROSS SECTIONS OF Pu238, Pu242, AND Am243 IN THE THERMAL AND EPICADMIUM REGIONS
Authors: Butler J. P. , Lounsbury M. , Merritt J. S.
Published: April 2011

Thermal neutron capture cross sections of 403 ± 8 b. for Pu238, 18.6 ± 0.8 b. for Pu242, and 73.6 ± 1.8 b. for Am243 have been measured by the activation method assuming 36.4 b. for the thermal neutron cross section of Co59. Samples of plutonium (90% Pu242 – 10% Pu238) were irradiated for 1 to 5 months in the NRX reactor. The growth of Pu239, Am243 (the daughter of the 5 hr. Pu243), and Cm244 (the daughter of the 25 min. Am244) was determined by mass analysis and by alpha spectrum analysis and total alpha counting. Resonance capture integrals (from 0.5 ev. to ∞) of 3260 ± 280 b. for Pu238, 1275 ± 30 b. for Pu242, and 2290 ± 50 b. for Am243 were found using cobalt and U238 as standards. Values of 48.6 b. and 282 b. were taken as the resonance integrals of Co59 and U238 respectively.The fission cross section of Pu242 was zero within experimental error.
PHOTONEUTRON EMISSION FROM Th232, U233, U238, AND Pu239
Authors: Katz L. , McNeill K. G. , LeBlanc M. , Brown F.
Published: April 2011

Measurements have been made of the numbers of neutrons emitted by the fissile materials Th232, U233, U238, and Pu239 under irradiation by betatron X-rays of various energies up to 23 Mev. Yield curves and corresponding cross section curves are given for these nuclides. At low X-ray energies it is found that the yield curves differ from those found with non-fissile heavy elements, corresponding to the fact that even at zero X-ray energy the fissile materials suffer (spontaneous) fission.
LOW TEMPERATURE RESISTIVITY OF THE TRANSITION ELEMENTS: COBALT, TUNGSTEN, AND RHENIUM
Authors: White G. K. , Woods S. B.
Published: April 2011

Experimental values are reported for the electrical resistivity from 1.5° to 300° K. and for the thermal resistivity from 2° to 120° K. of high purity cobalt, tungsten, and rhenium. The temperature variation of the components of the electrical and of the thermal resistance due to scattering by thermal vibrations is deduced and the possible evidence for the importance of s–d transitions is discussed briefly. The temperature of the superconducting transition in samples of rhenium is found to be close to 1.70° K., the value reported by Hulm (1954).
NEUTRON SPECTRUM OF AN ACTINIUM–BERYLLIUM SOURCE
Authors: Dixon W. R. , Bielesch Alice , Geiger K. W.
Published: April 2011

The neutron spectrum of an Ac227-α-Be source has been determined from proton recoil tracks in nuclear emulsions, and found to be in general agreement with the spectra of Po-α-Be and Ra-α-Be sources. Direct observation is limited to neutron energies above about 0.5 Mev. The question of neutrons below this energy is also considered.
STRUCTURE OF THE FUNDAMENTAL INFRARED BAND OF HYDROGEN IN PRESSURE INDUCED ABSORPTION
Authors: Gush H. P. , Nanassy A. , Welsh H. L.
Published: April 2011

The doublet structures observed by Coulon, Galatry, Robin, and Vodar (1955) in the QP and S(1) components of the pressure-induced fundamental infrared band of hydrogen have been reinvestigated under various conditions of temperature and pressure. It is concluded that the structures can be interpreted in terms of kinetic energy interactions which have already been shown to give rise to the main components, QP and QR, of the Q branch.
INFRARED INTENSITIES AND BOND MOMENTS IN SULPHUR DIOXIDE
Authors: Mayhood J. E.
Published: April 2011

New values have been obtained for the intensities of the three fundamentals of sulphur dioxide. They are A1 = 317 ± 8, A2 = 376±20, A3 = 2560 ± 70, in units of 1010 sec.−1 cm.−1 at S.T.P. The normal coordinate calculation gives values for the bond moment derivatives and for the molecular dipole moment which demonstrate that the amount of charge moving in all three vibrations is greater than that inferred from the equilibrium charge distribution. The involvement of unshared electrons is suggested.
THE FORWARD-SCATTERING OF RADIO WAVES FROM OVERDENSE METEOR TRAILS
Authors: Hines C. O. , Forsyth P. A.
Published: April 2011

The forward-scattering of radio waves from overdense meteor trails is treated from an elementary point of view. The results indicate that the same geometric factors enter this problem as enter the problem of forward-scattering from underdense trails, and that the transition between underdense and overdense trails occurs at the same value of charge density as in the backscatter case. These conclusions are not expected to be generally valid when applied to individual trails, but at least they should provide a valid basis for the interpretation and prediction of the effects produced statistically by a large number of trails.
THE EFFECT OF INTERACTIONS ON THE ANGULAR DISTRIBUTION OF γ-RAYS FROM AN ASSEMBLY OF ORIENTED NUCLEI
Authors: Daniels J. M.
Published: April 2011

The angular distribution of γ-radiation from an assembly of nuclei oriented by the magnetic h.f.s. method can be very much modified by interactions between the radioactive ions and other paramagnetic ions in the crystal. In order to calculate the effect of these interactions, an operator Γ is derived which represents the angular distribution of γ-rays from a radioactive nucleus. The angular distribution at any temperature is given by Spur(Γρ), where ρ is the statistical matrix [Formula: see text], [Formula: see text] being the Hamiltonian for the whole crystal. For a high temperature approximation, ρ is expanded in powers of 1/T. It is found that, for alignment by the magnetic h.f.s. method, the first term which contains interaction parameters is that in 1/T4, and an expression is given for the contribution of interactions to this term.At very low temperatures, perturbation theory is used to estimate the effect of interactions on the lowest nuclear energy state, and hence on the angular distribution of γ-rays. It is found that, if an external magnetic field is applied along a principal axis of the g-tensor of the radioactive ions, interactions have no influence on the angular distribution of γ-rays in the limit of large fields. It is also shown that Bleaney's restriction, that for a successful nuclear orientation experiment the broadening of the levels should be less than the hyperfine splitting, is not necessary in this case.
GROWTH CONDITIONS FOR STABILITY OF A CELLULAR SOLID-LIQUID INTERFACE
Authors: Holmes E. L. , Rutter J. W. , Winegard W. C.
Published: April 2011

Samples of zone-refined lead containing various amounts of silver as solute were solidified under well-controlled conditions to study the transition from cellular to dendritic freezing as a function of composition, speed of freezing, temperature gradient in the melt during freezing, and crystallographic orientation of the solidifying crystal. A comparison of the results of this investigation with those of Tiller and Rutter (1956) on alloys of tin in lead shows that to a first approximation the onset of dendritic freezing under any given growth conditions occurs at a critical value of the average solute concentration in the liquid at the solid–liquid interface, independent of whether the solute present is tin or silver.
THE CONSTITUTION OF NICKEL–GALLIUM ALLOYS IN THE REGION 0–35 ATOMIC % GALLIUM
Authors: Pearson W. B. , Rimek D. M.
Published: April 2011

The equilibrium diagram of nickel–gallium alloys has been revised to include a newly discovered Ni3Ga superlattice which forms peritectically at 1210° C. The new work shows that there is a very close resemblance between the Ni–Al and Ni–Ga systems in the nickel-rich region.
VIBRATION–ROTATION BANDS OF AMMONIA: II. THE MOLECULAR DIMENSIONS AND HARMONIC FREQUENCIES OF AMMONIA AND DEUTERATED AMMONIA
Authors: Benedict W. S. , Plyler Earle K.
Published: April 2011

A summary is given of molecular constants for NH3 and ND3, as derived from high-resolution infrared spectra of a number of fundamental, overtone, and combination bands. Preliminary estimates are given for the equilibrium moments of inertia, the molecular dimensions, and the force constants of the harmonic potential function. The average molecular dimensions in the equilibrium configuration are re = 1.0116 × 10−8 cm., he = 0.381 × 10−8 cm.
RADIATION AND SURFACE CURRENTS FROM A SLOT ON AN INFINITE CONDUCTING CYLINDER
Authors: Northover F. H.
Published: April 2011

The far field produced by an aperture in the surface of an infinite cylindrical antenna, whose interior is being electromagnetically excited in some way, has been calculated by Papas and others using a "saddle-point" method of approximation to the infinite integrals which express the external field. This method will not, however, serve to approximate to the far field near the antenna surface. Also, there seems to have been no attempt so far to estimate the order of magnitude of the error involved in using formulae derived by such methods. The object of the present paper is to remedy these deficiencies and to provide a basis for the calculation of the far field in wider regions than has so far been possible. In particular, the surface current distribution at large distances from the aperture has been worked out. Finally, a justification is given for the Papas procedure of integrating his approximation to the Poynting energy flux vector over the whole of the portion of the large sphere surrounding the aperture which is outside the cylinder itself.
HIGH RESOLUTION RAMAN SPECTROSCOPY OF GASES: XI. SPECTRA OF CS2 AND CO2
Authors: Stoicheff B. P.
Published: April 2011

The vibrational Raman spectra of CS2, C12O2, and C13O2, consisting of the strong Fermi diad ν1, 2ν2 have been photographed with a 21 ft. grating. In the spectrum of CS2, 12 additional sharp Q branches were observed in the region of the diad; three are due to isotopic molecules and the remainder are "hot" bands. The rotational structure of the strong ν1 band was also obtained. These measurements together with infrared data are used to determine the vibrational constants ωi0 and xik of CS2. The pure rotational spectrum of CS2, with rotational lines up to J = 94, yields the constants B000 = 0.10910 ± 0.00005 cm−1, D000 = 1.0 × 10−8 cm−1, and r0(C=S) = 1.5545 ± 0.0003 Å. For C12O2, the rotational structure of the diad was analyzed and the results are in agreement with recent infrared data.
OPERATION OF AN INVERTED-MAGNETRON GAUGE IN THE PRESSURE RANGE 10−3 TO 10−12 MM. Hg
Authors: Hobson J. P. , Redhead P. A.
Published: April 2011

A cold-cathode ionization gauge with axial magnetic field and radial electric field is described which is useful in the pressure range 10−3 to 10−12 mm. Hg and has a sensitivity of about 1 amp./mm. Hg. This gauge has the structure of an inverted magnetron with an auxiliary cathode which provides the initial field emission and allows the positive-ion current to be measured independently of the field-emission current. The operation and calibration of the gauge in a dynamic vacuum system is described for the pressure range 10−3 to 5 × 10−9 mm. Hg. Pressures ranging from 10−8 to 10−12 mm. Hg were obtained in sealed-off systems. Liquid-helium trapping was used for pressures below 10−10 mm. Hg. It is shown that the gauge gives a reliable indication of pressure below 10−10 mm. Hg when the pressure is determined by helium diffusion through the envelope.
PHOTONEUTRON THRESHOLD AND CROSS SECTION FOR 71Lu175
Authors: King H. J. , Katz L.
Published: April 2011

The neutron yield resulting from photoneutron reactions in Lu175 has been measured as a function of peak bremsstrahlung energy up to 23 Mev. The threshold energy for this reaction was found to be 7.77 ± 0.05 Mev. The giant resonance cross section has a peak value of 225 millibarns at 16 Mev., a half-width of 8.4 Mev., and an integrated cross section to 23 Mev. of 1.9 Mev-barns.
STUDIES OF SOME INFRARED FRAUNHOFER LINES
Authors: Godoli G.
Published: April 2011

The apparatus function of the Dominion Observatory solar infrared spectrometer was determined by laboratory observations of the CH4 band at 1.7 μ and checked by observations of the telluric CO2 band at 1.6 μ. The equivalent widths and the profiles of four Fe solar lines in the 1.6 μ region were determined with the same instrument at seven different points on the solar radius. The equivalent widths agree better with those determined by Pagel than with those determined by Mohler. The profiles, corrected for the apparatus function, suggest a very high ratio γ/γcl and a dependence of the kinetic temperature on the line strength.
SPIN–ORBIT INTERACTION IN NUCLEI
Authors: Nigam B. P. , Sundaresan M. K.
Published: April 2011

Brueckner's theory of nuclear structure has been used to estimate the spin–orbit interaction of a single nucleon interacting with the core arising from the tensor force of the two-body interaction. Using Yamaguchi's separable two-body interaction, the doublet splitting for Ca41 and O17 has been calculated (i) in the first Born approximation and (ii) with an exact solution of the reaction matrix in which the exclusion principle has been taken into account. It is found that the values of the splittings calculated exactly are smaller than the experimental values.
RADIATION FIELD OF AN ELLIPTIC LOOP ANTENNA WITH A CONSTANT CURRENT
Authors: Loh S. C. , Wong J. Y.
Published: April 2011

Expressions for the radiation field are derived for a loop antenna of elliptical shape assuming a uniform current distribution. It is found that the radiation pattern in the plane of the loop depends on both the size and the shape of the antenna. However, for small loops, the radiation pattern is independent of the shape and is essentially circular. Some calculated patterns for loops of different sizes and shapes are presented in order to illustrate the derived results.
OPTIMUM FILTER FUNCTIONS FOR THE DETECTION OF PULSED SIGNALS IN NOISE
Authors: Heaps H. S.
Published: April 2011

This paper is concerned with the optimum method of processing a signal received upon a background of noise. Determination is made of the transfer function of the process that maximizes the ratio of the average power of n successive samples of the output signal to the mean output noise power. For sufficiently large values of n the ratio is a close approximation to the ratio of the signal-to-noise energy contained in a sample of the output over a finite time. The maximum ratio is calculated when the input is a rectangular d.c. pulse upon white noise and when it is a cosine pulse upon non-white noise.The transfer function to maximize the ratio of signal voltage to noise power was determined in a previous paper. It is found that for the rectangular pulse the two methods of optimization lead to very similar ratios of signal-to-noise energy and that the third-order low-pass Butterworth filter produces a ratio of signal-to-noise energy that lies within a few per cent of the theoretical maximum. Such is not the case for the cosine pulse.
ON THE RATE OF CONVERGENCE OF THE SPHERICAL-HARMONICS METHOD FOR A SANDWICH REACTOR OF SMALL LATTICE PITCH
Authors: Davison B.
Published: April 2011

There are some cases where the spherical-harmonics-method calculations can be carried out purely algebraically, without specifying numerically the order of approximation used. Such is the problem of determining the spatial distribution of the thermal neutron flux in an infinite sandwich reactor of a small lattice pitch. The spherical-harmonics-method solution of this problem, in an arbitrary order of approximation, is compared with the exact solution. It is shown that if both are expanded in the Fourier series in terms of the optical depth, the nth term of the Fourier series for the spherical-harmonics-method solution differs from the corresponding term for the exact solution by the factor[Formula: see text]where N is the order of approximation used in the spherical-harmonics method and ε is one-half of the lattice pitch on the optical scale.This result should provide some guidance in assessing the rate of convergence of the spherical-harmonics method also for the more complex (and realistic) cases.
ANALYSIS OF METEORIC BODY DOPPLER RADAR RECORDS TAKEN DURING A GEMINID SHOWER PERIOD
Authors: Rao M. Srirama
Published: April 2011

The determination of the prevailing wind in the 80–100 km region of the upper atmosphere by a new method, involving the simultaneous use of a CW doppler radar at 30.02 Mc/sec and three-station pulsed radars at about the same frequencies, is presented in this paper. This method involves the determination of the exact location of each observed meteor train and the component of the velocity of its horizontal drift in the direction of the azimuth from Ottawa. A 40-minute period during the Geminid shower on the night of Dec. 10/11, 1948, has been selected for this investigation. Theory for the analysis of the body doppler records is briefly outlined. The prevailing wind speed obtained from the body doppler frequencies (fd) is 54 m/sec. The observed linear variation in the average fd with time, in the case of each meteor, has been explained as caused by the effective point of reflection drifting along its train towards the maximum echo duration level. Periodic fluctuations of fd of the order of 1–3 c.p.s., on the average, have also been observed. The above two phenomena can be explained from a postulate of atmospheric turbulence on a scale of about 1 km or above.
ON THE FLUORESCENCE OF AIR, EXCITED BY FAST ELECTRONS: LIGHT YIELD AS A FUNCTION OF PRESSURE
Authors: Grün A. E.
Published: April 2011

The fluorescence of air was excited by electrons of 4.2 to 43.7 kev and the light intensity If was measured by a 1 P 28 photomultiplier tube. The energy W transferred from the electrons to the gas molecules in a defined space could be accurately measured. The light yield, as defined by Φ = If/W, was experimentally determined as a function of the gas density ρ, or pressure p, respectively. The result is: 1/Φ + p/p′ with p′ = 11.5 mm Hg.
PHOTON CORRELATION IN COHERENT LIGHT BEAMS
Authors: Brannen E. , Ferguson H. I. S. , Wehlau W.
Published: April 2011

Experiments have been carried out in an attempt to detect any correlation between photons in coherent light rays using a coincidence circuit of resolving time 2τ = 8 ×10 −9 second. A Hg 198 electrodeless discharge tube under rf excitation was used to provide an intense monochromatic source of narrow line width (0.006 Å and 0.009 Å) at 5461 Å. A positive correlation was detected and compared with theoretical predictions.
SCATTERING FROM A SMALL ANISOTROPIC ELLIPSOID
Authors: Hurd R. A.
Published: April 2011

Scattering of an electromagnetic wave by a small ellipsoid having tensor permeability and dielectric properties is dealt with by expanding the fields as power series in λ−1. Consideration has been given to the first three terms of the expansion.
THE MAGNETIC FIELDS OF A FERRITE ELLIPSOID
Authors: Hurd R. A.
Published: April 2011

Approximate expressions are found for the internal and the adjacent external magnetic fields of a small ferrite ellipsoid under plane wave excitation. Consideration is given to the variation of apparent susceptibility with the size of the ferrite.
EXPERIMENTAL EVIDENCE FOR AXIAL VECTOR INTERACTION IN THE DISINTEGRATION OF Pr144
Authors: Graham R. L. , Geiger J. S. , Eastwood T. A.
Published: April 2011

A detailed study of the disintegration scheme of Pr144 has been carried out using lens spectrometers, scintillation spectrometers, and fast coincidence techniques. The 2293 kev β-component (1.3%) studied in coincidence with γ 691 has a predominantly first forbidden unique shape and the β–γ directional correlation is strongly anisotropic. The results indicate a probable spin-sequence 0−(β)2+(γ)0+, but the accuracy is not sufficient to exclude completely a 1− assignment for the Pr144 ground state. The β 803 component (1.0%) observed in coincidence with γ 2181 has an allowed shape and the β–γ directional correlation is isotropic. The shape of the total β-spectrum was studied in a double lens spectrometer having good anti-scattering properties using sources of Ce144 oxide sublimed onto 200 μg/cm2 Al leaf. Subtraction of a unique (Bij) shape 2293 kev 1.3% component and an allowed shape 803 kev 1.0% component yields the ground state β-spectrum. Analyses were made using the electronic functions of Zerianova which assume uniform charge distribution with ρ = 1.2 A1/3 10−13 cm as well as the point charge functions of Rose with ρ = 1.41 A1/3 10−13 cm. The observed spectrum shape can be explained on 0− to 0+ selection rules only by the axial vector interaction. Limits on the permissible tensor or pseudoscalar admixtures with the axial vector are discussed. No acceptable fit is possible with tensor, pseudoscalar, or any TP admixture (interfering or not) using Rose and Osborn's pseudoscalar formalism.
THE FREEZING POINTS OF HIGH PURITY METALS AS PRECISION TEMPERATURE STANDARDS: IV. INDIUM: THERMAL ANALYSES ON THREE GRADES OF CADMIUM
Authors: McLaren E. H.
Published: April 2011

An investigation of the freezing and melting temperatures of a sample of high purity indium (Cominco 99.999+ %) has been made. Plateaux of essentially constant (< ± 0.0001 °C) temperature with durations for over 1 hour are readily obtained on the cooling curves of induced freezes on this metal. The standard deviation of the plateau temperature (liquidus point) from a series of 24 induced freezes was ±0.0001 °C. The pressure effect on the freezing temperature of indium was found to be 0.0049 °C for 1 atm. Alloy melting ranges were measured following different types of freezing.An extensive intercomparison of liquidus points and alloy melting ranges has been made on a sample of 99.99% cadmium and two samples of 99.999+ % cadmium from different suppliers. The liquidus points of the high purity samples were indistinguishable using precision resistance thermometry but one sample melted over a slightly smaller range of temperature than the other. Both these samples showed minor arrests on melting curves after induced freezing and detailed analyses of the melting contours after various types of freezing indicated some evidence of characteristic structure inside a range of 0.002 °C.
ZEEMAN SPLITTING OF DONOR STATES IN GERMANIUM
Authors: Haering R. R.
Published: April 2011

The linear Zeeman effect of the 2p m = ± 1 donor states is calculated in the effective mass approximation. The resulting level splitting is independent of the longitudinal mass characterizing the ellipsoidal conduction band energy surfaces. This result is valid as long as the Zeeman splitting of the m = ±1 states is small compared to the energy difference between the 2p m = 0 and the 2p m = ± 1 states. The Zeeman pattern to be expected in germanium is plotted as a function of the angle between the magnetic field and the (100) direction.
THE DECAY OF Os191 AND Os193
Authors: Nablo S. V. , Johns M. W. , Goodman R. H. , Artna A.
Published: April 2011

The beta- and gamma-ray spectra of Os191 and Os193 have been studied with a magnetic beta-ray spectrometer, scintillation spectrometers, and coincidence circuits. The 14-hour isomer of Os191 decays via a 0.0742-Mev (M3) transition. Gamma rays of energy 0.0418 (100%, E3), 0.0809 (1%, M1 + E2), 0.1287 (100%, M1 + E2), and 0.1858 (0.1%) Mev have been found to be associated with the 14.6 ± 0.3 day decay of Os191 and an extension of the accepted decay scheme proposed. The following 19 transitions have been associated with the 31.5 ± 0.5 hour decay of Os193: 0.0730 (14%), 0.1068 (~1%), 0.1393 (10%), 0.180 (0.3%), 0.196 (0.1%), 0.243 (~0.2%), 0.2485 (0.3%), 0.2514 (0.4%), 0.278 (0.6%), 0.2810 (1.6%), 0.2885 (0.3%), 0.2994 (0.4%), 0.314 (0.3%), 0.3218 (1.7%), 0.3620 (0.6%), 0.3878 (1.6%), 0.4604 (4.1%), 0.4857 (0.3%), and 0.5585 (2.2%). The internal conversion coefficients for all the stronger transitions suggest that they are M1 + E2 in character. The decay energy of Os193 is 1.132 ± 0.005 Mev. Fermi analyses and beta–gamma coincidence experiments have established excited states of Ir193 at 0.073, 0.139, 0.281, 0.362, 0.460, and 0.559 Mev above the ground state. Six otherwise unclassified weak gamma rays can be accommodated if levels at 0.247, 0.315, and 0.613 Mev are included in the decay scheme.The activation cross sections of Os184 and Os190 are (2.2 ± 0.5) × 103and 5.3 ± 2 barns respectively, relative to Seren's value of 1.6 ± 0.4 barns for Os192.
AIR-MASS REFRACTIVITY IN CENTRAL CANADA
Authors: Hay D. R.
Published: April 2011

A study of air temperature, humidity, and pressure profiles above Maniwaki, Quebec, for the year 1957 shows that the four types of air masses have distinctive refractivities. It is shown also that the air masses may be identified through their dry and total refractivities. For a typical air-to-ground communication path, the mean effective-earth's radius varies from 1.26 to 1.37 times the true radius for the four types of air mass.
THE K–LL AUGER SPECTRUM OF 94Pu239
Authors: Ewan G. T. , Geiger J. S. , Graham R. L. , MacKenzie D. R.
Published: April 2011

The K–LL Auger spectrum of 94Pu239 has been examined using a high resolution π√2 β-ray spectrometer with a proportional counter detector. Seven lines have been observed in the Auger spectrum with the following energies and relative intensities.[Formula: see text]The presence of seven lines in this K–LL Auger spectrum is in disagreement with theoretical predictions based on pure j–j coupling and supports, rather, the recent theoretical treatment of Asaad and Burhop. The energies of the observed lines are in satisfactory agreement with their theoretical predictions but discrepancies exist in the relative intensities.
ON THE THEORY OF FLOW OF UNDERGROUND FLUIDS IN COMPRESSIBLE STRATA
Authors: Scheidegger A. E.
Published: April 2011

The problem of flow of a fluid within a compressible porous medium is investigated. It is shown that in general, the motion of the fluid cannot be separated from that of the medium. This leads to a very complex problem of consolidation. However, considerable simplification can be made in applications to the flow of underground fluids. In that case, the general geometry of the consolidation can be predicted since the latter can take place in the vertical direction only. Furthermore, in many cases it is possible to neglect the volume compressibility of the porous matrix.Two cases have been considered: that of local isotropy of stress and permeability and that of local anisotropy of these two quantities. The basic differential flow equation for the two cases is deduced.
MULTIPLE NEUTRON CAPTURE IN THE MIKE FUSION EXPLOSION
Authors: Cameron A. G. W.
Published: April 2011

The constant ratio of yields of successive even or odd mass number nuclides produced in the Mike fusion explosion of 1952 implies an approximate constancy of the corresponding neutron capture cross sections for neutrons near 100 kev for the nuclei between U238 and U254. A discussion is given of the physical quantities on which the neutron capture cross sections depend, particularly radiation widths, nuclear level spacings, and neutron binding energies. It is concluded that conventional mass formulas are probably wrong in predicting a large decrease in neutron binding energy as one goes from U238 to U254. It is possible that the addition of a direct symmetry term to the mass formula might repair this difficulty. Another possibility is that an extra diffuseness of the nuclear surface in neutron-rich nuclei would reduce the Coulomb energy of the nucleus, thus stabilizing neutron binding energies.
THE THERMAL EXPANSION OF CUBIC BARIUM TITANATE (BaTiO3) FROM 350 °C TO 1050 °C
Authors: Bland J. A.
Published: April 2011

The lattice spacing of cubic barium titanate (BaTiO3) has been measured as a function of temperature by means of a Unicam X-ray camera. The relation between a0 (in Å) and t between 350 °C and 1050 °C is:[Formula: see text]The maximum systematic error in a0 is 0.0005 Å. The linear expansion coefficient varies in an approximately linear fashion between 10.8 × 10−6 per °C at 350 °C to 17.5 × 10−6 = per °C at 1050 °C.
THE CHANGE OF RESISTANCE OF HYDROPHILIC FILMS SUBJECTED TO CONSTANT VOLTAGE
Authors: Niven C. D.
Published: April 2011

Graphs illustrate changes in resistance of gelatin and cellophane films when voltage is applied to them over a period of time and the polarity is then reversed. The similarity in these graphs, as well as other evidence, suggests that the mechanism of conduction for gelatin applies also to cellophane. Riehl's theory is very slightly modified and used to explain the results.
QUASI-PERSISTENT CURRENTS IN RINGS COMPOSED OF SUPERCONDUCTING AND NON-SUPERCONDUCTING REGIONS
Authors: Fink H. J.
Published: April 2011

A number of rings composed of a superconductor (Pb, In) apart from a small insert of normal metal (Cu) perpendicular to the current flow have been investigated between 1.30° K and 4.33° K for Pb–Cu and between 1.30° K and 3.20° K for In–Cu. It was found that for samples with good electrical contact the decay of the magnetic field due to the current is exponential and that the effective resistance increased compared with the bulk resistance of Cu by approximately 2.1 for the Pb–Cu rings and by 18.5 for the In–Cu rings. Two different thicknesses of the Cu inserts (0.0125 cm and 0.0053 cm) were used and it was found that the resistivity of the thin Cu insert increased with respect to the thick foil by 16% for the Pb–Cu system and by 36% for the In–Cu system. Part of this relative increase can be explained as a size effect due to electron scattering in the Cu insert. The effective resistance of the Pb–Cu rings shows a maximum at approximately 3.4° K. The resistance of the In–Cu samples decreases by about 10% between 3.2° K and 1.3° K. The resistivity of the Cu foil when measured separately was constant for the above temperature range. For samples with "poor" electrical contact (probably due to some copper oxide on the insert) two definite relaxation times were observed. For these samples the effective resistance was current and temperature dependent and it was decreasing for decreasing currents and decreasing temperatures. This can be explained in terms of a rectification effect of the two oxide layers on the insert. The decay of the magnetic field of the ring is consistent with the decay of a current in an L–R circuit.
THE DESTRUCTION OF SUPERCONDUCTIVITY IN TANTALUM WIRES BY A CURRENT
Authors: Fink H. J.
Published: April 2011

The transition from the superconducting to the normal state of various pre-stretched tantalum wires carrying current was investigated. When the resistance of the wire jumps discontinuously from the superconducting to the normal or intermediate state as a current is passed through it, then this current is defined as the critical current Ic. For temperatures T < (Tc−5 millidegrees K) the resistance of the wire jumps directly from zero resistance to its normal value at the critical current, such that the total cross section of the wire goes effectively into the normal state. Between (Tc−5 millidegrees K) and Tc the resistance of the wire jumps at Ic to any fraction of the normal resistance between approximately zero and one. For constant temperatures the resistance–current plots show a large hysteresis effect. The transition temperature, Tc, of the various samples is strongly dependent upon their normal resistivity at helium temperatures. If the wires with a small constant current (4.2 ma) flowing in them are cooled from above the transition temperature, the resistance decreases above Tc and approaches zero at approximately Tc, where Tc is defined by the extrapolation of the Ic–T curve to Ic = 0. If the wires are heated from below Tc the same resistance–temperature curves are reproduced.
A 6Σ–6Σ TRANSITION IN CrH
Authors: Kleman Bengt , Uhler Ulla
Published: April 2011

The infrared band system of CrH has been photographed at high dispersion. Rotational analyses of the 0–0 and 0–1 bands are given. The transition is shown to be a 6Σ+–6Σ+. The upper 6Σ-state shows an extended perturbation. Rotational and vibrational constants for the two states are given. The application of theoretical expressions for the fine structure splitting in 6Σ-states is discussed and approximate values of the splitting constants in the observed states have been derived. The corresponding system of the isotope molecule CrD was also photographed and a vibrational analysis has been carried out. Finally the electronic configurations of the molecular states and the nature of the perturbing state are discussed. The ultraviolet systems of CrH are briefly mentioned.
ABSOLUTE STANDARDIZATION OF RADIOACTIVE NEUTRON SOURCES: II. THE USE OF THE F19(α, n)Na22 REACTION
Authors: Geiger K. W.
Published: April 2011

Fluorine has only one stable isotope, F19. If neutrons are produced by the F19(α, n)Na22 reaction the neutron output can be calculated from the yield of the resulting radioactive Na22. The growth of Na22 (half-life, 2.58 years) has been measured in a neutron source consisting originally of 1.6 curies Po210 mixed with CaF2 powder. Since Na22 is a positron emitter, discrimination against γ-rays from Po210 and from nuclear reactions could be achieved by detecting the two positron annihilation quanta in coincidence. The Na22 growth has been followed over 20 months and is in agreement with the theoretical growth curve. Comparison with a calibrated Na22 source yielded a neutron emission rate of (10.70 ± 0.25) × 104 sec−1. This resulted in a neutron emission rate of (3.16 ± 0.10) × 106 sec−1 for the Ra-α-Be source of the National Research Council, in good agreement with (3.22 ± 0.05) × 106 sec−1 obtained by a neutron thermalization method.
PHOTONEUTRON CROSS SECTION OF Ni58
Authors: Roalsvig J. P. , Haslam R. N. H. , McKenzie D. J.
Published: April 2011

The reaction Ni58(γ, n)Ni57 has been investigated between 12- and 24-Mev maximum photon energy. The absolute yield value at 22 Mev was found to be much lower than reported previously. Also, a shorter half-life of Ni57 was obtained. The cross section was determined using two different methods.
ON TOROIDAL FUNCTIONS
Authors: Loh S. C.
Published: April 2011

The general solutions of Laplace's equation in toroidal co-ordinates have been derived, both for the three-dimensional and the axial symmetrical cases. Also, the general theory and properties of toroidal functions have been briefly outlined.The numerical tables for the zonal and the tesseral toroidal functions were calculated by the I.B.M. 650 Computer at the University of Toronto, and are included in the present paper.
THE LYMAN BANDS OF MOLECULAR HYDROGEN
Authors: Herzberg G. , Howe L. L.
Published: April 2011

The Lyman bands of H2 have been investigated under high resolution with a view to improving the rotational and vibrational constants of H2 in its ground state. Precise Bv and ΔG values have been obtained for all vibrational levels of the ground state. One or two of the highest rotational levels of the last vibrational level (v = 14) lie above the dissociation limit. Both the [Formula: see text] and ΔG″ curves have a point of inflection at about v″ = 3. This makes it difficult to represent the whole course of each of these curves by a single formula and therefore makes the resulting equilibrium constants somewhat uncertain. This uncertainty is not very great for the rotational constants for which we find[Formula: see text]but is considerable for the vibrational constants ωe and ωexe for which three-, four-, five-, and six-term formulae give results diverging by ± 1 cm−1. The rotational and vibrational constants for the upper state [Formula: see text] of the Lyman bands are also determined. An appreciable correction to the position of the upper state is found.
THERMAL CONDUCTIVITY OF POWDERS
Authors: Laubitz M. J.
Published: April 2011

The effective thermal conductivity of several powders of reasonably uniform particle size, and one powder of graded particle size, was measured in the temperature range of 100 °C to 1000 °C. Most of the results can be very satisfactorily explained by assuming that the effective conductivity of the powder is composed of two parts, the first part being a two-phase gas–solid conductivity, and the second an equivalent radiation conductivity.
THE OCCURRENCE OF (n, 3n) REACTIONS IN A NUCLEAR REACTOR
Authors: Eastwood T. A. , Roy J. C.
Published: April 2011

The reactions Bi209(n, 3n)Bi207 and Au197(n, 3n)Au195 have been observed to occur in NRX, a thermal neutron reactor. Competing reactions leading from Bi209 or Au197 to the same products have been shown to be negligible. Within the uncertainties of the methods used the yields of Bi207 and Au195 are about those expected on the basis of neutron evaporation from the compound nucleus formed by the amalgamation of the incoming neutron and the target nucleus.
EVIDENCE FOR NEUTRONS WITH AN ENERGY OF 20.3 MEV IN THE NRX REACTOR
Authors: Roy J. C.
Published: April 2011

Experimental evidence is presented on the occurrence of the C12(n, 2n)C11 reaction in the NRX reactor. The probability of occurrence of the competing processes C12(γ, n)C11 and C12(p, pn)C11 is discussed. A comparison is made of the observed reaction rate with the one predicted by the formula representing the energy distribution of the prompt neutrons from the thermal fission of U235. Since the threshold of the C12(n, 2n)C11 reaction is 20.3 Mev, observation of the reaction in the NRX reactor means that there are neutrons with an energy of at least 20.3 Mev produced in fission.
Kr 86 AND Hg 198 WAVELENGTH STANDARDS
Authors: Baird K. M. , Smith D. S.
Published: April 2011

New values are given for the vacuum wavelengths of six lines of Kr 86 and five lines of Hg 198 in the visible spectrum. The wavelengths were referred to the Kr 86 primary standard line, 6057.80211, by a series of very careful measurements over a period of several years. The accuracy with which wavelengths can be compared by present methods is discussed at some length.
PARAMAGNETIC RESONANCE LINE SHAPES
Authors: Swarup Prem
Published: April 2011

A study of the line shape of the transitions of various concentrations of Cr+++ ion in potassium cobalticyanide and potassium aluminum alum single crystals has been made at 9300 Mc/s. The line shape is found to change gradually from Lorentzian to Gaussian with chromium concentration. Lorentzian shape of gadolinium ion in lanthanum ethyl sulphate and exchange narrowing in case of free radical and copper sulphate are reported. The line width and relative intensity of the transitions in a highly dilute cyanide salt at 4.2° K are plotted and it is found that the intensity followed the maximum of the matrix element squared for various transitions. The value of g is found to be 1.992. The actual concentration of Cr+++ in dilute salts is less than the concentration of the solution from which they are grown by more than a factor of 10 as the dilution is increased.
THE NEUTRON YIELD FROM HEAVY ICE TARGETS BOMBARDED WITH PROTONS BELOW THE D(p, n)2p THRESHOLD
Authors: Singh P. P. , Griffiths G. M. , Ssu Y. I. , Warren J. B.
Published: April 2011

In connection with some experiments on the gamma-ray yield from the D(p, γ)He3 reaction using heavy ice targets a considerable yield of neutrons was found even for proton bombarding energies well below the D(p, n)2p threshold of 3.3 Mev. The yield, excitation function, and angular distribution of this neutron yield have been investigated both experimentally and by means of theoretical calculations. These studies confirm the suggestion that the neutrons are produced by a secondary reaction in which deuterons, scattered in the target by incident protons, collide with further target deuterons to produce D(d, n)He3 reactions.
THE C–X SYSTEM OF
Authors: Carroll P. K.
Published: April 2011

The [Formula: see text] system of [Formula: see text] has been investigated under high resolution in the region 1650–2000 Å. Fifteen bands of the system have been analyzed and accurate rotational constants and other data for the [Formula: see text] state have been derived. Anomalies in the rotational and vibrational structure are discussed. Some evidence in favor of a predissociation between the levels ν = 2 and ν = 3 of the [Formula: see text] state is presented.
THE GREY TINWHITE TIN TRANSITION IN TIN–MERCURY ALLOYS
Authors: Smith R. W.
Published: April 2011

The characteristics of the transition between white tin (β) and the grey modification (α) in zone-refined tin containing various amounts of mercury have been investigated. From dilatometric measurements, it is shown that the transition temperature of the reaction:[Formula: see text]is −8.15° ± 0.1 °C. Above this temperature, mercury will attack grey tin to form a white tin amalgam. The compound HgSn12, previously reported not to undergo transformation, is shown to transform below this temperature. Measurements are given of the rates of growth of islands of grey tin on the surfaces of a number of tin–mercury alloys at −30 °C. These indicate that the rate of β→α transformation is virtually independent of the mercury content of the alloy.The results are discussed and a mechanism is advanced to account for the large displacement of the [Formula: see text] transition temperature observed when mercury is alloyed with tin in contrast to the small changes brought about by other additions.
THE DECAY OF Bi208
Authors: Millar C. H. , Eastwood T. A. , Roy J. C.
Published: April 2011

It has been observed that Bi208 decays mainly by K- and L-electron capture to the 2.615-Mev first-excited level of Pb208. Decay to known Pb208 levels above the 2.615-Mev level has been shown experimentally not to occur in more than 3% of the Bi208 disintegrations, in agreement with an analysis of the mass differences in this region which indicates that such decay modes are energetically impossible. Positrons are not emitted in more than 5% of Bi208 disintegrations. The value of the ratio of K X-rays to 2.615-Mev γ-rays has been measured to be 0.23 ± 0.01. Assuming that the ground state of Bi208 is 5+ and that the theory of Brysk and Rose is accurate in the region near the K-capture threshold, this ratio measurement leads to a value of 2.807 Mev for the total decay energy of Bi208. This agrees with the value 2.75 ± 0.10 Mev obtained from reaction cycle analysis. New measurements of the Bi208 half-life have revealed an error in the previous measurement, the best value now being 7.5 × 105 years to within a factor of three. Incidental to the main experiment an upper limit of 0.5% has been measured for the positron decay of Bi207.
THE PHOTODISINTEGRATION OF NEON
Authors: Hay H. J. , Warren J. B.
Published: April 2011

A proportional counter, filled to 4-atmosphere pressure with pure neon, and a cylindrical gridded ionization chamber, filled to 9-atmosphere pressure with neon containing some helium, have been irradiated with the gamma-ray flux from a thick lithium target bombarded with 500-kev protons. Pulse height analysis led to the assignment of the following photodisintegration cross sections in millibarns:Ne20(γ17.6, α)O16, 0.05 to the ground state of O16, 0.67 to the 6.06- and 6.14-Mev levels of O16, 1.80 to the 6.91- and 7.12-Mev levels of O16;Ne20(γ14.8, α)O16, 0.086 to the ground state, about 1.0 to the 6.06- and 6.14-Mev levels;Ne20(γ17.6, p)F19, 21 to the ground and low-lying levels at 110, 197 kev in F19, about 5 to the 1.35- and/or 1.57-Mev levels in F19;Ne22(γ17.6, α)O18, 0.76 to the ground level.The Ne20(γ, α)O16 cross sections are in good accord with the selection rules put forward by Gell-Mann and Telegdi for the photodisintegration of an even–even nucleus.
ELECTRICAL BREAKDOWN IN XENON AND KRYPTON AT ULTRAHIGH FREQUENCIES
Authors: Bradford H. M. , Fraser D. M. , Langstroth G. F. O. , MacDonald A. D.
Published: April 2011

Breakdown electric fields have been measured in a resonant cavity for xenon and krypton gases in the pressure range of 0.05 to 100 mm of mercury, at a frequency of 2800 Mc/sec. Extensive precautions were taken to ensure gas purity.
THE TEMPERATURE–TIME DEPENDENCE OF THE TRIPLE POINT OF WATER
Authors: Berry R. J.
Published: April 2011

The important, but elusive, temperature–time dependency of the triple point of water has been thoroughly investigated in 10 triple point cells from two sources. During the first 2 days after preparation of the cells, the temperature was found to increase by amounts ranging from 0 to 5 × 10−4 °C with the average rise being 2 × 10−4 °C. After the second day the temperature continued to rise at a rate of about 0.1 × 10−4 °C per day for about a week and finally stabilized. In practice, if an ice mantle in a cell is allowed to age for about three days before the cell is used the temperature should be reproducible to about 10−1 °C.A series of experiments are described which suggest that this initial temperature rise may well be due to the growth of crystals in the ice and/or strains in the freshly prepared ice. The slow rise after the second day could be accounted for by crystal growth. These two possibilities are discussed in detail and a formula relating the temperature to crystal size is compared with the observed results.Tests in pyrex cells up to 5 years old showed that they contain no significant amount of impurities and, therefore, that the segregation of impurities during the freezing process is not likely to be the cause of the initial temperature variations.On the assumption that the above explanations are true, a number of methods of eliminating this troublesome initial temperature rise were tested. Since none of these tests was completely successful, methods of extending the usefulness of old mantles were examined.Different methods of preparing and using the cells were critically examined; the earlier method of supercooled freezing was found to be quite inadequate. The effect of different thermal bonds in the thermometer well and of different cell environments was investigated. As a result of this work a new importance is attached to the standard practice of melting the inner layer of ice next to the thermometer well.The effect of the temperature–time dependency on previous measurements of the difference in temperature between the ice and triple points of water is discussed.