bluuebunny/crossref_metadata_2025 huggingface dataset:
THE DESIGN OF AN AUTOMATIC RECORDING ELECTROSCOPE AND ITS USE TO DETERMINE HALF-LIVES IN RADIOACTIVE DECAY
Authors: Bartholomew Rosalie M. , Brown F. , Howell W. D. , Shorey W. R. J. , Yaffe L.
Published: April 2011

An automatic recording electroscope has been constructed and used to determine short half-lives in radioactive decay. The operation of the instrument has been tested by comparing it with both a manually operated electroscope and a 4 π type proportional β counter. The instrument produces results which are at least as accurate as any with which they may be compared. The half-lives of Co60m and Al28 have been measured as 10.47 ±.02 min. and 2.27 ±.02 min. respectively.
EFFECT OF RADAR SENSITIVITY ON METEOR ECHO DURATIONS
Authors: McKinley D. W. R.
Published: April 2011

Meteor echo durations were observed simultaneously with two radar systems having a power sensitivity ratio of 33 db. An experimental relation between echo duration and system sensitivity is obtained which shows that the duration of meteor echoes varies slowly, but significantly, with system parameters. Curves are furnished to correct observed durations to zenithal durations, applicable to any system using a horizontal half-wave dipole antenna.
AN EXPERIMENTAL STUDY OF COUNTING LOSSES DUE TO DEAD-TIME EFFECTS
Authors: Westcott C. H. , Kirkaldy J. S. , Greenberg J. S.
Published: April 2011

When using counting methods for studying instantaneous reactions produced with pulsed accelerators such as synchrotrons or synchrocyclotrons, the systematic errors in counting due to dead-time effects may be considerable. One of us has already published a discussion of the simpler cases of pulsed single-channel counting; the present paper describes experimental investigations designed to extend our knowledge of these corrections, especially to cases of coincidence counting. In Part I of the present paper, the method and apparatus are described, together with calibration procedure; in the course of checking results already known from computation, defects in the functioning of the equipment were uncovered and the correction of these defects is described.Part II of the paper deals with the problems of coincidence counting at high speed but without the complication of a pulsed source. Difficulties arise in this case unless the rate of occurrence of coincidences is much smaller than the counting rates in the separate counters, a condition which may not be satisfied in many cases in the study of high energy reactions. The corrections for this case have therefore been investigated experimentally and a relatively simple correction formula obtained when chance coincidences are negligible. The dependence of the number of additional chance coincidences on coincidence gate-width is determined both theoretically and experimentally, with satisfactory agreement.In Part III the investigation is extended to pulsed coincidence counting. A theoretical formula is developed neglecting chance coincidences, for pulse-lengths less than twice the dead-time, and experiments confirm the results and indicate how to extrapolate for longer pulse-durations. A first-order formula for the chance coincidences is also obtained and confirmed.In all cases near-rectangular pulse-forms are used, but the equipment can readily be modified to study other forms. For the guidance of the user, the principal formulae adopted for determining counting corrections are collected in Appendix III at the end of this paper.
PILE NEUTRON CAPTURE CROSS SECTIONS OF Co60* (10.5 MIN.) AND Co60 (5.25 YR.)
Authors: Brown F. , Wolfson J. L. , Yaffe L.
Published: April 2011

Activity of approximately 105 min. half-life has been detected in samples of Co59 irradiated at high neutron fluxes in the NRX reactor. By a study of the yield as a function of neutron flux and time of irradiation this activity was demonstrated to be due to Co61 (105 min.) formed by neutron capture in Co60. The pile neutron capture cross sections were found to be 95 ± 45 barns and 6.0 ± 1.4 barns for the Co60* (10.5 min.) and Co60 (5.25 yr.) isomers respectively.
A QUANTUM-STATISTICAL THEORY OF LIQUID HELIUM
Authors: Buckthought K.
Published: April 2011

A model for liquid He4 is set up in which the atoms are regarded as an assembly of Bloch waves following Bose-Einstein statistics. The potential field inside the liquid is estimated. Numerical calculation of the thermodynamic functions shows fair agreement with experiment. The λ-temperature and its variation with pressure are calculated, and are in good agreement with observed values. The model is also applied to liquid He3. The variation of entropy with temperature is calculated.
INTERPRETATION OF THE FLUCTUATING ECHO FROM RANDOMLY DISTRIBUTED SCATTERERS. II
Authors: Wallace P. R.
Published: April 2011

The determination of the probability distribution for the magnitude of a radar echo from randomly distributed scatterers is a standard problem of the "random walk" type. We are concerned with the information to be gained about the scatterers from observation of the echoes, and the methods whereby this information may be extended. The method of averaging independent signals is investigated, and compared with the method of continuous averaging, which is found to be somewhat better. By appropriate variation of frequency of the radiation, it is found possible to obtain effectively independent determinations from a given region, and hence to derive more precise information about it. Finally, the continuous variation of signal with time is studied, and a simple picture of the development of the signal proposed. The Markoff method is used throughout.
THE EMISSION SPECTRUM OF ALUMINUM MONOFLUORIDE I
Authors: Naudé S. M. , Hugo T. J.
Published: April 2011

Two band systems of the emission spectrum of AlF are described, viz. the far ultraviolet A1Π − X1Σ system discovered by Rochester in absorption, and a new system due to a 1Σ − A1Π transition in the region 8175 Å–6670 Å. A revised vibrational analysis of the A1Π − X1Σ system is given as well as the vibrational and rotational analyses of the new system, which is the C1Σ − A1Π system of AlF.
THE DECAY OF Cd105
Authors: Johnson F. A.
Published: April 2011

The isotope Cd105 (55 min.) has been produced by the Ag107 (p,3n) reaction in the McGill University synchrocyclotron and has been investigated by means of a 180° spectrograph of high resolution, a lens spectrometer, and a scintillation spectrometer.The positron end point was found to be 1.691 ± 0.005 Mev. and the Fermi plot of the spectrum was straight down to about 800 kev. where a slight upward curvature began. Internal conversion lines found in the 180° spectrograph indicated γ-rays of energies 25.50, 27.69, 263.0, 292.5, 308.0, 312.1, 317.1, 320.5, 324.9, 336.3, 340.7, 347.0, 433.1, and 606.7 kev. High energy internal conversion lines found in the lens spectrometer beyond the end point of the positron spectrum were assigned to γ-rays of energies 1.908, 1.957, 1.995, 2.045, 2.277, and 2.318 Mev.In addition lines assigned to Ag105 have been recorded. These correspond to γ-rays of energies 64.0, 280.8, 319.4, 331.5, 344.9, 392.6, and 443.2 kev., of which that of 331.5 kev. has not been reported previously.
A SUGGESTED METHOD FOR STUDYING THE MECHANISM OF ENERGY TRANSFER IN COLLISIONS
Authors: Wu Ta-You
Published: April 2011

It is shown that information can be obtained concerning the nature of the energy transfer process in collisions in which an excited atom (or molecule) A′ transfers its energy of excitation to another atom (or molecule) B,[Formula: see text]by comparing the experimental value of the ratio of the cross section σq and the σex of the inverse process with the theoretical values of this ratio for various modes of excitation of B, which values can be readily obtained from statistical mechanical considerations alone. For example, for the study of the nature of the "quenching" collisions, the ratio σq/σex can be determined from a measurement of the intensity of the radiation emitted by A′ as a function of time. Such measurements are possible with the photomultiplier and electronic timing circuit techniques now available.
THE TOPOGRAPHY OF SOLID–LIQUID INTERFACES OF METAL CRYSTALS GROWING FROM THE MELT
Authors: Elbaum C. , Chalmers B.
Published: April 2011

An improved technique of separating the liquid portion of the metal from the adjacent crystal has been developed. Microscopic examination of the interfaces prepared by this method has revealed a new surface structure. It has been found that the presence or absence of the structure depends on the crystallographic orientation of the specimen. The structures have been observed in all of the metals investigated in the present work, namely lead, tin, and zinc. A detailed study of the structure has been made in the case of lead. It was observed that, when the angle between the macroscopic plane of the interface and either the (111) or the (001) plane was less than a certain critical value, the interface consisted of steps or terraces approximately 0.001 mm. high. A mechanism for the formation of those steps is proposed.
THE PULSE HEIGHT DISTRIBUTION FROM BORON TRIFLUORIDE PROPORTIONAL COUNTERS IRRADIATED WITH 4.87-MEV. NEUTRONS
Authors: James D. B. , Kubelka W. , Heiberg S. A. , Warren J. B.
Published: April 2011

Two boron trifluoride proportional counters, one containing normal isotopic boron and the other containing boron enriched to 96% B10, have been irradiated with 4.87-Mev. neutrons from the reaction D(d, n)He3. In addition to the reactions B10(n, α)Li7 and B10(n, α)Li7* with Q-values of 2.79 Mev. and 2.31 Mev. respectively, two other reactions have been observed. These are (i) F19(n, α)N16* with a Q-value of −1.77 ± 0.15 Mev. and (ii) either B10(n, p)Be10 or, much more probably, B10(n, t)Be8 with a Q-value of 0.35 ± 0.20 Mev. Owing to the presence of these two reactions, the analysis of complex fast-neutron spectra by the use of such counters is not feasible.
LOW ENERGY NEUTRON CROSS SECTION OF MANGANESE
Authors: Krotkov R.
Published: April 2011

The total neutron cross section of Mn55 has three (predominantly scattering) resonances in the energy range 300–2500 ev. In the present paper these resonances are examined in detail from the point of view of the R matrix formalism. It is found that quite good (but not perfect) agreement with the experimental cross section curve is obtained by assigning (in order of increasing resonance energy) spins (2, 3, 3) and neutron widths (23, 11, 395 ev.) to the resonances. The addition of a constant increment ΔR11 = 0.16 × 10−12 cm. representing the contribution of distant, positive energy, J = 3 resonances to the R matrix element for s-neutron scattering improves agreement with experiment on the high energy side of the highest energy resonance. The (n, γ) cross section at 0.025 ev. is fitted well by a constant radiation width of 0.5 ev. However, with no set of parameters was it possible to fit both the experimental total cross section curve, and the observed coherent scattering cross section at 0 ev., although the sign of the latter was accounted for correctly. The discrepancy is 2.0 barns (calculated) compared to 1.7 barns (observed).
THE ν3 INFRARED BAND OF AMMONIA
Authors: Cumming C.
Published: April 2011

An absorption band in gaseous ammonia at 3 μ is observed at high resolution and attributed to the doubly degenerate fundamental ν3. The constants ν0 = 3442.9, A0 = A1 = 6.13, A1ζ = 0.29, and B1 = 9.75 cm.−1 describe the band. Many of the observed lines are doublets. This doubling is a result of the inversion of the ammonia molecule and the value 1.1 cm.−1 is calculated for the inversion doubling of the 0010 state.
THE FISSION YIELDS OF THE CESIUM ISOTOPES FORMED IN THE THERMAL NEUTRON FISSION OF U235 AND THE NEUTRON ABSORPTION CROSS SECTION OF Xe135
Authors: Petruska J. A. , Melaika E. A. , Tomlinson R. H.
Published: April 2011

The absolute fission yields of the cesium isotopes occurring in the thermal neutron fission of U235 have been determined with a mass spectrometer using isotope dilution techniques. Values of 6.59%, 6.41%, and 6.15% have been obtained for the yields of Cs133, Cs135, and Cs137 respectively. The neutron absorption cross section of Xe135 has also been measured to be 866 times greater than that of B10 for a Maxwellian distribution of neutron velocities corresponding to a neutron temperature of 57 °C. This ratio gives a thermal neutron absorption cross section of 3.47 × 106 barns for Xe135 assuming it is a 1/ν detector.
RADIO OBSERVATIONS OF THE IONOSPHERE AT OBLIQUE INCIDENCE
Authors: Chapman J. H. , Davies Kenneth , Littlewood C. A.
Published: April 2011

A description is given of an automatic method of using the radio pulse technique at oblique incidence to investigate the structure of the ionosphere. Sweep frequency photographic records were taken for the path Ottawa–Saskatoon (2355 km.). The records obtained confirm the validity of the theory relating vertical incidence to oblique incidence propagation. Sweeps showing such phenomena as E layer cutoff, transmission of the Pedersen ray, multiple reflections, are shown. It is found that the F1 layer is the important propagating layer rather than the F2 layer under certain conditions. Hence conventional methods of predicting frequencies over long distances require modification in these circumstances.
AURORAL HEIGHTS OVER WEST-CENTRAL CANADA
Authors: Currie B. W.
Published: April 2011

A complete analysis of the parallactic photographs of aurora taken at Chesterfield, N.W.T., (63.3°N., 90.7°W.) in 1933 show (a) a marked maximum in the heights of the lower limits of both homogeneous arcs and bands and auroral structures with rays between 100 and 110 km., (b) a mean height of the lower limit of arcs and bands of 108.2 km., (c) a mean height of the lower limit of auroral structures with rays of 113.4 km., (d) a decrease of height with increasing intensity, and (e) no definite evidence of a change of height with time after sunset. The results suggest that heights of aurora as observed from Northern Canada are slightly higher than of aurora observed from Norway. This may be due to the locations of the two regions relative to the zone of maximum auroral occurrence. No exceptionally low heights were observed at Chesterfield. Remeasurements of the 1933 photographs for Saskatoon (52.1°N., 106.6°W.) indicate that one arc was definitely below the 70-km. level, and possibly below the 60-km. level.
THE NEW ISOTOPES Cd104 AND Ag104
Authors: Johnson F. A.
Published: April 2011

Two new neutron deficient isotopes Cd104 (59 min.) and Ag104 (27 min.) have been produced by the reaction Ag107(p, 4n)Cd104 at 50 Mev. in the McGill University synchrocyclotron and by the subsequent growth of silver from the cadmium. These isotopes have been investigated by means of a 180° spectrograph of high resolution, a lens spectrometer, and a scintillation spectrometer. Chemical methods of identification have also been employed. Ag104 has been found to emit a positron spectrum of end point 2.70 ±.01 Mev. and a γ-ray of 556.2 kev. which is thought to be in series with the positron spectrum. The origin of a γ-ray of energy 118.4 kev. which appears to be converted in palladium is at present unknown. A tentative decay scheme is proposed. Cd104 appears to decay primarily by K-capture since no positron spectrum was observed which could be assigned to this isotope. Four γ-rays, of energies 66.7, 83.6, 123.6, and 134.2 kev., have been definitely assigned to this isotope on the basis of K−L differences shown by conversion lines; on the basis of relative L line intensities and K/L ratios the two low energy γ-rays have been shown to represent M1 transitions. Other conversion lines were found whose origin and element of conversion are unknown.
SOME NOTES ON THE THEORY OF THERMAL-NEUTRON REACTORS
Authors: Stewart J. D.
Published: April 2011

Equations for the asymptotic steady-state distribution of neutrons in homogeneous and lattice-type reactors are derived without making any assumptions about the mechanism of diffusion, except the obviously necessary one that the probability for a neutron which is born at one given point to be captured at a second given point is a function only of the distance between these two points. The equations are seen to be of a form that admits of exponential solutions, these are written down, and equations for the Laplacians are derived. A clear-cut definition of the migration area of a lattice reactor is given, and it is pointed out that in a reactor of this type there is no unique value of the Laplacian but rather a range of values.
MAGNETIC SUSCEPTIBILITY OF LOW RESISTIVITY n-TYPE GERMANIUM
Authors: Hedgcock F. T.
Published: April 2011

Some results on the magnetic susceptibility of n-type low resistivity polycrystalline germanium as observed between room and liquid nitrogen temperatures are presented. The contribution to the susceptibility from both the free and bound charge carriers has been derived from the experimental results and appears to vary inversely with temperature. An effective mass for the charge carriers in n-type germanium is found to be 0.16 of the free electron mass.
A MODIFICATION OF THE ONE-PARTICLE FORMULA FOR NUCLEAR GAMMA-RADIATION
Authors: Wallace P. R.
Published: April 2011

The one-particle theory of isomeric γ-transitions in nuclei consistently overestimates the probability per unit time of decay. It is shown that, by modifying the one-particle model to take account of the readjustment of the wave functions of all the nuclear particles during the predominantly one-particle transition, satisfactory agreement with experiment can be obtained. The fact that odd-proton transitions are depressed more than odd-neutron ones is attributed to the exchange character of the force giving rise to the readjustment.
THE FAR ULTRAVIOLET (C–X) BANDS OF N2+
Authors: Wilkinson P. G.
Published: April 2011

Emission bands of the N2+ C–X system in the vacuum ultraviolet have been obtained under high resolution. The rotational analysis confirms the assignment as a [Formula: see text] transition and the rotational constants obtained are in substantial agreement with previous investigations. The unusual intensity distribution in the ν′ = 3 progression and perturbations in the ν′ = 0, 1, and 2 levels of the C state are in agreement with the theory of inverse predissociation in the ν′ = 3 level.
SELECTION RULES AND TEMPERATURE DEPENDENCE OF THE FIRST-ORDER RAMAN EFFECT IN CRYSTALS
Authors: Theimer O.
Published: April 2011

Starting from the most general scattering formulae, the current theory of the Raman effect in crystals is modified in such a way as to remove the well-known discrepancies between theory and experiment concerning the selection rules for calcite and similar crystals. A distinction is made between electrons in delocalized crystal orbitals and electrons in localized atomic or molecular orbitals and it is shown that only the latter produce a Raman scattering in agreement with the unmodified theory. The general formula for the scattering by delocalized electrons is analyzed and it is found that the magnitude of the components [Formula: see text] of the first-order polarizability (qi normal coordinate of the scattering lattice vibration) depends on the wave vectors Q′ and Q″ of incident and scattered light. The wave vector dependence of the first-order polarizability requires selection rules for the first-order Raman effect which do not correspond to the full symmetry of the scattering crystal but only to the symmetry operations of the group of Q = Q′ – Q″ which leave Q unchanged. These modified selection rules are shown to be compatible with experiment. The influence of mechanical anharmonicity and of polarizability derivatives of higher order on the first-order Raman effect is also discussed. It is found that these non-linear effects offer no satisfactory explanation for the great intensity of forbidden lines in the Raman spectrum of some crystals. Concerning temperature effects the non-linear terms in the intensity formulae are found to be of greater importance and are tentatively suggested as being responsible for the anomalous temperature dependence of low frequency external lattice vibrations.
RADIATION PATTERNS OF A DIELECTRIC-COATED AXIALLY-SLOTTED CYLINDER
Authors: Hurd R. A.
Published: April 2011

The azimuthal radiation pattern of an axial slot in a dielectric-coated circular cylinder is derived. Some patterns are computed, and a comparison with experiment made.
ABSORPTION SPECTRA OF ETHYLENE AND ETHYLENE-d4 IN THE VACUUM ULTRAVIOLET. II
Authors: Wilkinson P. G.
Published: April 2011

The absorption spectra of ethylene and ethylene-d4 have been investigated in the 1300 Å to 1500 Å region using the first order of a 21-ft. vacuum grating spectrograph. Vibrational constants for the v2(ag) stretching vibration and the v4(au) twisting vibration have been determined for each of the observed five Rydberg states. The torsional oscillator–rotator treatment has been applied to the observed twisting data, and potential barriers hindering free rotation of 500 to 1200 cm−1 were obtained. It is concluded that the stable equilibrium configuration of the Rydberg states is not of D2h symmetry but is probably bent or staggered.
ON THE DISTRIBUTION OF THE PRODUCT OF DIODE DETECTOR WAVEFORMS
Authors: Webb E. L. R.
Published: April 2011

The probability distribution of the product of two waveforms such as come from the diode second detectors of radio receivers is examined over the whole range of signal to noise ratios. Computed curves of probability density are given for small and moderate values of signal to noise ratio and the limiting form for large signal to noise indicated. The pure noise case is the only one immediately available in terms of tabulated functions. Compared to the Rayleigh distribution it rises much faster, reaches its maximum sooner and lower, and decays much more slowly. The very large signal to noise ratio case approaches an impulse function. Estimates of mean and variance are given.
THE RAMAN SPECTRUM OF ETHYLENE
Authors: Feldman T. , Romanko J. , Welsh H. L.
Published: April 2011

The vibrational Raman spectrum of ethylene was photographed at gas pressures of 1–3 atm. with a reciprocal linear dispersion of 10.5 cm.−1 per mm. The rotational structures of the totally symmetric bands, ν1 and ν3, were analyzed using an approximate asymmetric top model; only the Q branch of ν2 was observed. In the complicated structure of the non-totally symmetric ν5, band a series of O, SQK branches was identified and the band origin determined as 3102.5 cm.−1. A satisfactory interpretation of a broad maximum at 1662 cm.−1 could not be given.
EMISSION BAND SPECTRA OF NITROGEN THE LYMAN-BIRGE-HOPFIELD SYSTEM
Authors: Lofthus Alf
Published: April 2011

The near ultraviolet part of the emission spectrum of nitrogen has been photographed under high resolution. Thirteen bands of the [Formula: see text] system (Lyman–Birge–Hopfield) have been analyzed and new vibrational and rotational constants obtained. Combining the observed data with those obtained by Stoicheff from the Raman spectrum of nitrogen, refined equilibrium constants for the ground state were obtained. The predissociation in the α1Πg state was observed.
SHELL EFFECTS ON THE SPACING OF NUCLEAR LEVELS
Authors: Newton T. D.
Published: April 2011

Recent measurements of resonances in slow neutron total cross sections yield good estimates of the average level spacing, D, in medium and heavy nuclei. These spacings show large variations, by factors of 103 to 105, in the region of magic numbers of nucleons. There are also variations by smaller factors between nuclei with even and odd numbers of protons or neutrons. The even–odd effect is a co-operative phenomenon; it can be approximately treated by redefining the ground state to be used for a Fermi gas model. After this correction the gas model should predict D with reasonable accuracy since it is required only to define the density of a complete set of states. The magic number variations are shown to be fitted by an improved approximation to the single-nucleon level density. This is obtained from the observed sequence of single-particle spins and the assumption that the energy interval between spin subshells is constant. Fifty-two observed spacings are fitted by a two-parameter formula with an average uncertainty factor 3. Many of the larger remaining differences between observation and the predictions of the model are qualitatively explicable as expected departures from this uniform spacing hypothesis.
THE DIURNAL BEHAVIOR OF SUDDEN COMMENCEMENTS OF MAGNETIC STORMS AT AGINCOURT
Authors: Jacobs J. A. , Obayashi T.
Published: April 2011

The diurnal variations in the frequencies of sudden commencements of magnetic storms are examined, using the magnetograms from Agincourt for the period from 1946 to 1953 inclusive. The occurrence frequencies of sudden commencements exhibit an apparent diurnal tendency which has its minimum in the morning hours and maximum in the afternoon. The frequency distributions for several groups classified by their amplitudes, however, show different diurnal variations from one another. In order to confirm such local-time effects, a statistical analysis of the shape of sudden commencements has been made, and each sudden commencement classified according to its shape. Results show the following diurnal characteristics. A pronounced augmentation of the sudden commencement impulse occurs in the afternoon hours. In the morning the initial rise of sudden commencements is usually slight and they are frequently inverted in the H-trace, although some of them are quite clear in the D-trace. The local-time variation of the horizontal magnetic vectors at several stages of the initial phase is also estimated statistically. These results suggest that the diurnal control of the magnetic variation must be due to some additional field produced in the earth's upper atmosphere at the time of sudden commencement, tending to modify the primary cause.
A MICROWAVE WAVEGUIDE TROMBONE PHASE SHIFTER
Authors: Adey Albert W. , Britton Joyce
Published: April 2011

A microwave phase shifter is described which is based on the sliding principle of the trombone and which involves the telescoping together of two snugly-fitting sections of rectangular waveguide of different cross-sectional dimensions. Quarter-wave transformers are used to reduce the reflection at the change of waveguide cross-section. An attempt is made to increase the bandwidth of the instrument by making the transformers of different lengths. A phase change of several wavelengths is possible with an error of approximately plus or minus one degree.
INFLUENCE OF VIBRATION–ROTATION INTERACTION ON THE INTENSITIES OF PURE ROTATION LINES OF DIATOMIC MOLECULES
Authors: Herman Robert , Rubin Robert J.
Published: April 2011

The magnitude of the effect of the vibration–rotation interaction on the intensities of pure rotation lines of diatomic molecules has been calculated for two different molecular models, the anharmonic oscillator and the rotating Morse or Pekeris oscillator. The intensity correction for the anharmonic oscillator has been obtained by adapting the contact transformation formalism for calculating second-order corrections to the energy to the calculation of first-order corrections to the matrix elements of the electric moment as suggested by H. H. Nielsen. The correction to the line intensity for vibrationless transitions of the anharmonic oscillator is found to be[Formula: see text]The results obtained here are also in complete agreement, to first order, with the results obtained earlier by Herman and Wallis for the 1–0 and 2–0 vibration–rotation line intensities. In the case of the Pekeris or rotating Morse oscillator the correction to the pure rotation line intensity is of the same form as above, namely,[Formula: see text]but exhibits minor differences which can be explained in terms of the difference in the vibrational potential energy function in the two cases.
HIGHER-ORDER FOCUSING IN THE π√2 β-SPECTROMETER
Authors: Lee-Whiting G. E. , Taylor E. A.
Published: April 2011

The expansion coefficients of that magnetic field which gives best focusing in the high-aperture double-focusing spectrometer have been determined to the sixth order. The analytical calculations have been checked by numerical integration of the equations of the orbits. The third- and fourth-order coefficients published by Stoker et al. (1954) are not in agreement with our results.
SPALLATION YIELDS FROM HIGH ENERGY PROTON BOMBARDMENT OF HEAVY ELEMENTS
Authors: Jackson J. D.
Published: April 2011

The Monte Carlo calculations of McManus and Sharp (unpublished) for the prompt nuclear processes occurring upon bombardment of heavy elements by 400 Mev. protons are combined with a description of the subsequent neutron evaporation to determine spallation cross sections for comparison with experiment. The model employed is a schematic one which suppresses the detailed characteristics of individual nuclei, but gives the over-all behavior to be expected. Many-particle and collective effects such as alpha particle emission and fission are ignored. The computed cross sections are presented in a variety of different graphical forms which illustrate quantitatively the qualitative picture of high energy reactions first given by Serber (1947). The calculations are in general agreement with existing data when fission is not an important effect, but the agreement does not imply a very stringent test of the various features of the model.
THE EFFECTS OF GRAIN BOUNDARIES ON THE PLASTIC DEFORMATION OF ZINC CRYSTALS
Authors: Craig G. B. , Chalmers B.
Published: April 2011

The tensile plastic deformation of single-crystal and tricrystal specimens of zinc was investigated by analysis of the external change in shape of the specimens, and of the changes in X-ray diffraction patterns. It was demonstrated that the single crystals deformed by slip on the basal plane, but pyramidal as well as basal slip occurred in specimens containing grain boundaries.
THE ANGULAR DISTRIBUTION AND YIELD OF THE REACTION F19(p, α0)O16
Authors: Clarke R. L. , Paul E. B.
Published: April 2011

The yield of the ground state alpha particles from the F19(p, α0)O16 reaction has been studied from an energy of 1.3 Mev. to 2.7 Mev. The observed angular distributions were analyzed in terms of a Legendre polynomial expansion by the method of least squares. Six resonances were found in the energy region studied, at bombarding energies of 1.358 Mev., 1.709 Mev., 1.853 Mev., 2.11 Mev., 2.31 Mev., and 2.58 Mev. The widths and peak cross sections of these resonances are respectively: (54 ± 10 kev., 46 ± 5 mb.), (140 ± 5 kev., 55 ± 6 mb.), (132 ± 5 kev., 77 ± 8 mb.), (75 ± 25 kev., 10 ± 2 mb.), (80 ± 25 kev., 32 ± 5 mb.), and (300 ± 25 kev., 51 ± 10 mb.). Their spins, parities, channel spin mixtures, and partial widths are discussed.
ELASTIC SCATTERING OF 20-MEV. PROTONS BY OXYGEN AND NITROGEN
Authors: Chow R. H. , Wright Byron T.
Published: April 2011

The absolute angular distributions for 20-Mev. protons elastically scattered by O16 and N14 were determined using the external beam of the frequency-modulated cyclotron at the University of California, Los Angeles. The distributions for the two elements were found to be similar except for the appearance of a more pronounced first minimum in the O16 distribution. The locations of the maxima and minima seem to indicate that simple diffraction effect is responsible for their presence. The cross sections range from about 1 barn per sterad. to 4 mb. per sterad. between 15° and 165° in the laboratory system. The standard deviations due to statistics range from [Formula: see text] to 10%.
ESTIMATED FISSION FRAGMENT MASSES
Authors: Hay I. W. , Newton T. D.
Published: April 2011

The mass excesses, M − A, of atoms in the fission fragment region have been empirically estimated by extrapolation of β-decay Q-values using the regularities found by Way and Wood (1954). The resulting estimates of the energy release in fission may indicate the most probable charge and, roughly, the range of charge for a given mass ratio of primary fission fragments.
THE INFLUENCE OF IMPURITIES ON THE MACROMOSAIC STRUCTURES OF TIN AND LEAD
Authors: Atwater H. A. , Chalmers B.
Published: April 2011

The properties and characteristics of arrays of low-angle boundaries which appear upon freezing of single crystals of tin and lead from the melt are shown to be dependent upon the amount and kind of impurities in the freezing liquid. The boundary-direction angle as a function of lattice orientation and impurity content in crystals frozen at speeds greater than 18–20 mm./minute is employed as an observational quantity. Measurements of boundary-direction are given for various impurity concentrations and types. Mechanisms for the determining of the boundary directions are proposed.
EMISSION BAND SPECTRA OF NITROGEN: A STUDY OF SOME SINGLET SYSTEMS
Authors: Lofthus Alf
Published: April 2011

Ten bands of Gaydon's and Herman's singlet systems and eight new bands have been photographed under high resolution and analyzed in detail. Two of the new transitions were shown to be [Formula: see text], the upper state being in one case identical with Watson's and Koontz's state g, and one new transition to be 1Δg—ω1Δu in type. It is proposed that the new state 1Δg has the same electron configuration as the [Formula: see text] state. Two bands in the red and one band in the ultraviolet could not be assigned with certainty. Local perturbations in the [Formula: see text] state were observed and shown to be caused by the ν = 1 level of the [Formula: see text] state. Observed pecularities in the rotational structure of most of the upper states are proposed to be indicative of a transition from case b′ to d′ coupling. In some cases pronounced decreases in branch intensities were observed, indicating predissociations probably caused by "forbidden" intercombination processes. Identification of the electronic structure of the higher singlet states in terms of Rydberg orbitals is discussed. Rotational and vibrational constants and excitation energies are presented.
THE ENERGY OF ALPHA PARTICLES FROM U234, U238, AND Th232
Authors: Harvey B. G. , Jackson H. G. , Eastwood T. A. , Hanna G. C.
Published: April 2011

The α-particle energies of U234, U238, and Th232 have been measured with a grid ionization chamber. The electronic equipment was designed to provide low noise, high resolution, and good long term stability. Ra226, Em222, Po218, Po214, and Po210 were used as energy standards. An investigation was made of the corrections to the measurements due to variation in pulse rise-time, source thickness, and imperfect shielding of the collector by the grid. It was found that the experimentally observed resolution was satisfactorily accounted for by the combination of these factors and the noise and ionization straggling.Alpha particle pulse heights were measured in terms of the output of a precision pulse generator. The corrected pulse heights were related to the energies of the standard sources by a two-parameter least squares calculation; the standard deviation was never greater than 5 kev. On extrapolating to zero ionization the line so obtained intercepted the energy axis at 83 kev. The α-particle energies deduced using this line were: U234 4.768 ± 0.003, U238 4.195 ± 0.005, Th232 4.007 ± 0.005 Mev.
NEW TYPE OF MAGNETIC TRANSITION IN Mn3ZnC
Authors: Brockhouse B. N. , Myers H. P.
Published: April 2011

Alloys with the approximate composition Mn3ZnC are known to be ferromagnetic but the saturation magnetization shows a maximum in the region of 231° K. X-Ray and neutron diffraction measurements are reported which demonstrate that at 231° K. there is a second order transition below which ordering of the manganese ions occurs, resulting in a tetragonal distortion of the normally cubic lattice and a complex magnetic structure. One possible magnetic structure is discussed. Above the transition the alloy is apparently a normal ferromagnetic substance.
THE NEAR ULTRAVIOLET ABSORPTION SPECTRUM OF 1,2,4-TRIFLUOROBENZENE VAPOR
Authors: Rao K. Narahari , Sponer H.
Published: April 2011

The vapor spectrum of 1,2,4-trifluorobenzene at 2810–2460 Å was obtained with a 3 meter grating in an Eagle mounting. The band at 37126 cm−1 was taken as the 0–0 band of the A′—A′ transition. The excited state vibrations 698, 746, 1274, and 1369 cm−1, which are totally symmetric, appear in progressions and combinations. Their correlation to vibrational modes is discussed. The 1274 belongs to a C—F bond stretching mode. Possibilities are discussed to explain the structure of the first group upon which the spectrum is built.
THE LATTICE SPACINGS OF NICKEL SOLID SOLUTIONS
Authors: Pearson W. B. , Thompson L. T.
Published: April 2011

New lattice spacing measurements in terminal nickel solid solutions with Cr, Mn, Co, Zn, Ga, Ge, In, and Sn solutes are reported and discussed, and the relationship of lattice distortion and the depression of the solidus temperature is examined in solid solutions of the First Long Period elements in nickel.
THE VELOCITY DEPENDENCE OF ČERENKOV RADIATION FROM μ-MESONS
Authors: Millar C. H. , Hincks E. P.
Published: April 2011

The intensity–velocity relationship of the Čerenkov light emitted by μ-mesons passing through Plexiglas has been studied for the velocity range 0.83c to 0.99970c (84 Mev. to 4.2 Bev.). No departure of the observed from the theoretical intensity was found in the high velocity region, in disagreement with the results of Bassi, Bianchi, and Manduchi (1952). In the low velocity region slightly less radiation was observed than expected, but this is attributed to an optical effect in the apparatus rather than to a departure from theory of the Čerenkov light emission.
STEADY STATE HEAT TRANSFER TO FULLY DEVELOPED TURBULENT FLOW IN A CURVED CHANNEL
Authors: Marris A. W.
Published: April 2011

A vorticity transfer analogy theory of turbulent heat transfer is developed first for the case of fully developed turbulent flow under zero transverse pressure and temperature gradients such as that in the annulus between concentric cylinders rotating with different angular velocities or in a "free vortex". The mean flow is assumed to be two-dimensional. The theory, which requires that the turbulence be statistically isotropic, yields a temperature distribution in agreement with experiment except in narrow regions immediately adjacent to the boundaries. An argument is given to show that the boundary layer thickness should be of the order of the reciprocal of the square root of the mean velocity, these boundaries are introduced, and Nusselt moduli are defined and their dependence on Reynolds and Prandtl numbers is investigated.The temperature distributions for the case of non-zero transverse temperature and pressure gradients, i.e. for the case of flow in a curved channel in which the fluid does not flow back into itself, are then obtained and the applicability of the simpler equations for zero transverse gradients to this case is investigated.
DIFFUSION IN MULTICOMPONENT METALLIC SYSTEMS
Authors: Kirkaldy J. S.
Published: April 2011

Onsager's phenomenological scheme for diffusion in multicomponent liquid systems is examined for suitability as a description of metallic interdiffusion. Subject to certain restrictions and approximations a set of non-linear differential equations is obtained which can be simply applied to important boundary conditions. A solution of the set for the system iron, carbon, silicon is shown to provide a good fit to Darken's experimental results.
A STUDY OF NUCLEON FORCES WITH REPULSIVE CORES: III. LOW ENERGY PROPERTIES OF THE LÉVY POTENTIAL
Authors: Preston M. A. , Shapiro J.
Published: April 2011

An attempt has been made to select the core radius and coupling constant of the Lévy potential for the interaction of two nucleons in order to fit the binding energy of the deuteron and the singlet state neutron–proton scattering length. It was found that these two quantities cannot be fitted simultaneously. For any given choice of coupling constant, a somewhat larger core radius is required to fit the deuteron binding energy than is required for the scattering length. This spin dependence of the core radius does not preclude the possibility of a fit to the low energy data with the Lévy potential.
MEASUREMENT BY PHOTOELECTRIC FRINGE SCANNING OF THE PRESSURE SHIFT OF Hg-198 EMISSION LINES
Authors: Baird K. M. , Smith D. S.
Published: April 2011

Photoelectric fringe scanning apparatus has been developed at the National Research Laboratories for the measurement of very small wavelength changes (of the order of 5 × 10−5 Å). This paper describes its application to a direct measurement of the shift of some of the visible lines of Hg-198 caused by the presence of the various rare gases used as a carrier. The values found for the shift in wave number are all of the order of 2 × 10−4 cm−1 per mm. (Torr) pressure and to the red, except for He, for which it is somewhat less than 1 × 10−4 cm−1 per mm. and to the blue.
THE GRAVITATIONAL FIELDS OF ELECTRIC AND MAGNETIC DIPOLES
Authors: Tauber Gerald E.
Published: April 2011

Einstein's field equations are solved for cylindrical symmetry in the presence of electric and magnetic singularities (dipoles).
THE FORMATION OF ANTISYMMETRIC WAVE FUNCTIONS
Authors: Trainor L. E. H.
Published: April 2011

The problem of forming antisymmetric wave functions is discussed, and it is shown that a convenient method developed previously by the author leads to the usual results.
MINIMUM SPARK BREAKDOWN AND GLOW VOLTAGES
Authors: Gambling W. A. , Crawford F. W.
Published: April 2011

Measurements of the spark breakdown voltage between carbon electrodes in hydrogen, argon, nitrogen, and air are given for ranges of the product p (mm. Hg) × d (cm.) between 0.1 and 1000 mm. Hg cm. The results show that in each gas Paschen's Law is obeyed for pd > 10 mm. Hg cm. For pd < 10 mm. Hg cm. deviations from Paschen's Law were observed at the longer gap lengths. The minimum spark breakdown voltage, Vsm, occurred near pd = 1 mm. Hg cm. The normal cathode-fall voltage, Vcn, was also measured, and was found to be less than Vsm in hydrogen, argon, and air, and greater than Vsm in nitrogen. A theoretical analysis is made which predicts the relationship Vcn = 1.110 Vsm and the reasons why this condition is seldom found in practice are discussed.
HIGH-DISPERSION TWO-DIRECTIONAL-FOCUSING β-SPECTROMETERS
Authors: Lee-Whiting G. E.
Published: April 2011

Momentum spectra of charged particles are often analyzed with the aid of magnetic focusing; in one type of spectrometer the particles move along a circular arc roughly perpendicular to the lines of force. It is shown that when the beam is turned through an angle of [Formula: see text] radians in a suitably shaped magnetic field a two-directional focus is obtained. For this type of instrument the dispersion increases rapidly as n is increased, while the aberrations remain roughly constant. Even for values of n in the range 3 to 7 an enormous gain in "luminosity" and a useful increase in the permitted source width should be obtained. Although practical difficulties are introduced by the use of paths of more than one complete revolution, these should not be insuperable if the size of the apparatus is large enough relative to the size of the source, especially if an odd value of n is used.
THE DECAY OF Au193 AND LEVEL SCHEME OF Pt193
Authors: Ewan G. T.
Published: April 2011

Au193 has been produced as the daughter of Hg193 formed by the reaction Au197(p, 5n)Hg193 in the McGill synchrocyclotron. The internal conversion spectrum and unconverted γ-ray spectrum have been examined using β-ray spectrometers, Nal spectrometers, and coincidence techniques. Au193 decays by electron capture to Pt193 with a half-life of 17.5 ± 0.2 hr. An upper limit of 0.08% per disintegration has been placed on the probability of emission of positrons in this decay. Twenty-eight γ-rays, all below 500 kev., have been observed associated with the decay of Au193. The first excited state of Pt193 has been shown to be at 12.7 kev. and the lifetime of this state measured as (2.2 ± 0.8) × 10−9sec. A level scheme is proposed for Pt193.
HIGH RESOLUTION RAMAN SPECTROSCOPY OF GASES: IX. SPECTRA OF H2, HD, AND D2
Authors: Stoicheff B. P.
Published: April 2011

The pure rotational lines and the Q branch lines of the 1–0 vibrational bands of H2, HD, and D2 have been photographed with a 21 ft. grating spectrograph. From these spectra, a complete set of constants for the ν = 0 and 1 levels of all three molecules have been determined. When these constants are combined with Herzberg's results of the forbidden infrared spectra of H2 and HD they lead to improved values of the electronic ground state constants of H2 and HD. The leading terms in the Dunham power series expansion of the potential are calculated for H2 and HD and are found to be mutually consistent. The isotopic relations are obeyed within experimental accuracy, and the small constants De, Be, and He, are in agreement with values given by theoretical formulae.
ON A REPORTED ISOMERIC STATE IN Mn54
Authors: McNeill K. G. , Prentice J. D. , Katz L. , Link W.
Published: April 2011

An attempt was made to detect the 2 minute isomeric state in Mn54 reported by Caldwell and Stoddart. Irradiation of pure Mn55 with various energy bremsstrahlung of 12 to 24 Mev. failed to disclose any (γ, n) reactions leading to this state. Iron targets irradiated by 13.5 Mev. neutrons failed to disclose any positron activity of 2 minute half-life resulting from an (n, p) reaction to this state. In view of these experiments we conclude that the existence of the reported isomeric state in Mn54 should not be accepted without reservation.
A STUDY OF THE APPROXIMATE THEORY OF AN ELASTIC THICK BEAM
Authors: Higuchi Seiichi , Saito Hideo , Hashimoto Chiaki
Published: April 2011

The flexural vibration of a thick beam is analyzed two-dimensionally by using the general equation of flexural motion. The characteristic equations and the frequencies of thick beams for the various end conditions are obtained and comparisons are made between the frequencies obtained from the present calculations and those from the elementary theory of a thin beam.
ROTATIONAL TEMPERATURES MEASURED IN AURORAE AT CHURCHILL, MANITOBA
Authors: Montalbetti R.
Published: April 2011

A series of auroral spectra showing the 0–0 N2+ band have been obtained at Churchill, Manitoba. Rotational temperatures ranging from 230° K. to 480° K. have been deduced. These are in agreement with measurements made at Saskatoon, Saskatchewan, and indicate that there is no latitude effect. A vertical temperature gradient of some 6° K./km. is suggested by the observatio