摘要:

Selective reflection from mercury and cadmium vapors in the neighborhood of the resonance lines was investigated quantitatively using incident light of continuous spectral distribution. For a given experimental arrangement the lowest vapor density (atoms per cubic centimeter) at which selective reflection could be detected at Hg 2537 Å, Cd 2288 Å, and Cd 3261 Å was inversely proportional to the oscillator strength (f-value) of the absorption line. Contours of the selective reflection of the Hg 2537 Å and Cd 2288 Å lines were obtained over a large range of vapor densities up to 80 × 1018atoms per cc. At this density the cadmium reflection extended over several thousand cm.−1compared to about a hundred cm.−1for mercury. The general features of the reflection contours can be explained by the theory of reflection from an absorbing medium. Fitting a theoretical curve to the experimental reflection contour yields values of the oscillator strength and the damping constant. For Hg 2537 Å and Cd 2288 Å thef-values are 0.0268 and 1.40 respectively, in good agreement with those found by other methods. The damping constant, γ, varies as the square root of the number of atoms per cubic centimeter, indicating that the mechanism of selective reflection is not the same as that for absorption and emission. An empirical areal law for selective reflection confirms the relationship. A shift of the resonance frequency of the order of magnitude of the coupling shift calculated by Weisskopf was observed for Hg 2537 Å. Deviations from theory at both high and low pressures were observed for Cd 2288 Å. The low pressure deviation takes the form of a line of residual intensity at the resonance frequency, which may be due to a different kind of selective reflection.

ISSN:1923-4287    

DOI:10.1139/cjr50a-008

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

The electronic circuits known as an integrator-expander were constructed for the accurate control of the X-ray energy of the University of Saskatchewan betatron. The over-all design and operation of the circuits are discussed. The design of the energy bias control, amplifier, and trigger portions of the circuit is original, and these are described in some detail.

ISSN:1923-4287    

DOI:10.1139/cjr50a-009

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

In general, diffraction relations which were developed for optical purposes have been found to be useful in the prediction of electromagnetic fields due to radiating apertures but, because many radio-optical measurements must be made so close to the aperture that the mathematical approximations in the Fresnel field relation often are invalid, new relations, free from these approximations, must be developed. The optical, Fraunhofer relation has been found to predict the distant field with good accuracy and for this reason the Fresnel field is calculated from the distant field equation by the Fourier transform method. The calculation is found to result in an integral which reduces to Fresnel's integral when the standard optical approximations are made in it. The integral has not been evaluated.

ISSN:1923-4287    

DOI:10.1139/cjr50a-010

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Axial measurements have been made of the resolving power of photographic projection printing systems. Besides the usual diffuse and specular systems a third system was considered in which the aperture of the projection lens is not entirely filled by the image of the source. If the relative aperture of this system is calculated considering the source image as the entrance pupil of the lens, then at small relative apertures this system has greater resolving power than the other systems. However, there is no advantage in using the third system at small relative apertures. At large to moderate relative apertures there are only very slight differences among the three systems. Diffusion screens placed in a condenser enlarging system may cause considerable reduction in resolving power if the lens was not previously filled by the image of the source. This effect, and also the high contrast that is very frequently present, are thought to be the origin of references in the literature to sharper pictures obtainable with condenser enlarging systems.

ISSN:1923-4287    

DOI:10.1139/cjr50a-011

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

The isotopic structures of the Zn I resonance lines 2139 Å (4s21S0 − 4s4p1P1) and 3076 Å (4s21S0 − 4s4p3P1) excited in an atomic beam source have been resolved with a Fabry–Perot etalon. Shifts in cm.−1relative to the Zn64component are + 0.016 and + 0.033 in 2139 Å, and + 0.023 and + 0.046 in 3076 Å for Zn66and Zn68, respectively. When the normal mass shifts are subtracted, the residual shifts for Zn68are + 0.010 (2139 Å) and + 0.030 cm.−1(3076 Å). The field effect theory of isotope shift predicts equal shifts and the specific mass effect predicts unequal shifts for the1Pand3Plevels. Therefore the difference of these residuals is a specific mass effect. The difference has the sense predicted by the specific mass theory and its value, 0.020 cm.−1, is a large fraction of the observed shifts. Thus the specific mass effect must be taken into account before the field effect theory can be used to obtain nuclear properties from isotope shifts in intermediate elements.

ISSN:1923-4287    

DOI:10.1139/cjr50a-012

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Four lines of the 2–0 band and four lines of the 3–0 band of the quadrupole rotation–vibration spectrum of H2have been observed and measured using effective absorbing paths of 10 to 50 km. atm. From this spectrum improved values of the rotational and vibrational constants of H2in its electronic ground state have been obtained.

ISSN:1923-4287    

DOI:10.1139/cjr50a-013

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

A recording magnetometer operating on the saturated core inductor principle has been constructed. An inverse feed-back system supplies a current to neutralize the field being measured. The neutralization is such that the sensitive element is maintained within 2 or 3 gammas of zero field. The feed-back current is measured by a recording milliameter. Using a feed-back coil of suitable dimensions, the record gives a direct measure of the field.

ISSN:1923-4287    

DOI:10.1139/cjr50a-014

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

With the requisite chemical treatment, specific minerals will assume a surface radioactivity by undergoing reactions with radioactive ions in solution. It is essential that the mineral have a suitably tarnished or coated surface, for in general no exchange will occur on a fresh surface. It is suggested that the radioactivity so induced could be used in conjunction with a mechanical device to separate and concentrate the valuable minerals in an ore, or to control hydro-metallurgical plant processes.

ISSN:1923-4287    

DOI:10.1139/cjr50a-015

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

The diffusion equation for electrons in a nonuniform field is solved and the breakdown condition derived. The breakdown condition is expressed in such a manner that an effective characteristic diffusion length Λeis determined; the meaning of Λeexpresses the equivalent characteristic diffusion length for uniform electric fields. From the experimental breakdown fields, in which the electric field is uniform, Λeis determined and used to predict theoretical breakdown curves for the nonuniform cases. Theory and experiment are compared, the agreement verifying the correctness of the approach.

ISSN:1923-4287    

DOI:10.1139/cjr50a-016

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Six-figure tables of the function μ(z) = e−αz/γM(α: γ: z) have been computed for the following values of the parameters, α = 0.001, 0.01, 0.1 (0.1) 1.0, 0.25, 0.75; γ = 0.5 (0.5) 2.0, andz = 0 (0.1) 1.0 (0.5) 8. They may be used in conjunction with tables of the exponential function for accurate values of the confluent hypergeometric function.

ISSN:1923-4287    

DOI:10.1139/cjr50a-017

出版商:NRC Research Press    

年代:1950

数据来源: NRC