Twenty uranium L x-ray transitions have been measured using a commercial, sealed off, uranium target x-ray tube. Twelve plutonium L x-ray transitions have been measured in conventional x-ray fluorescence from a 5.86-g sample. All lines were measured with high precision using the two-crystal spectrometer, and corrected for the effects of temperature on the grating space of calcite, the effects of vertical divergence, and the effects of crystal diffraction pattern asymmetry. The wavelengths corresponding to these transitions are given in terms of the x-unit (where the latter is so defined that the wavelength of the Mo Kai line is 707.8490 x-units) with relative errors of less than 15 ppm (parts per million) in the case of U, and less than 30 ppm in the case of Pu.
Certain approximations commonly used in the absolute calibration of a scanning monochromator are examined in terms of the response of the instrument to a monochromatic input. The absolute irradiance due to any spectral feature in the neighborhood of lambda(0) is commonly computed from the expression W = AB(lambda(0))/H(lambda(0)) where A is the area of the spectral feature as recorded by the monochromator output trace, B(lambda) is the spectral irradiance of a standard source, and H(lambda) is the response of the monochromator to B(lambda) when the monochromator corresponds to wavelength lambda. As an example, approximations used in justifying such calculations are examined and applied to an Ebert 0.5-m monochromator. For the case chosen, the approximation is shown to be valid to an accuracy of 1.5% to 2%, depending upon assumptions made in the calculation. It is found that the most serious error for this example is introduced by changes in the sensitivity of the monochromator over a wavelength interval comparable with that of the spectral feature under investigation. A second source of error is found to be the change in the irradiance of the standard source over a wavelength interval comparable to the instrument resolving power.
The addition-of-velocities hypothesis, which Kantor recently claimed to have verified, has been investigated using a different experimental arrangement. A laser beam was'passed through a moving mica window, which might be considered as a Huygens-type moving source of light. An interferometer was built with which to detect and measure any change in speed of the emitted light. The apparatus allowed investigation of: the effects of window speed, which could be varied continuously up to 63m/sec; direction of window motion with respect to direction of propagation; and the effects of air in the beam path. Emission theory as used by Kantor predicted a-I fringe shift; however, no shift was observed under any conditions. The estimated sensitivity of the method is 1/20 fringe. Our results are therefore consistent with the second postulate of special relativity, but not with Kantor's hypothesis.
A technique for obtaining emission cross sections in laboratory beam studies is presented, including effects on the cross section due to polarization of the emitted light. Systematic analytical errors arising from optical problems are analyzed and evaluated for a typical spectral feature. The primary sources of error are shown to arise from the particular geometry used in the optical measurements, the variation of the calibrating light source over the bandwidth of the emission feature, and the variation of the responsivity of the optical system over the bandwidth.
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