Pionic X-ray intensities per captured negative pion in various elements

Pionic X-ray intensities were measured with Ge spectrometers for various atomic transitions in 30 elements (atomic numbers Z=3 to 83). The Z-dependence of the pionic X-ray yield in the same transition showed sharp yield maxima in the neighborhood of the Z values of closed atomic shells in addition to the broad maximum expected from competition of radiative transitions with the Auger effect and absorption by strong interaction with the nucleus, respectively. The variation in the X-ray yields with Z could be made plausible in terms of a simple model, in which the initial angular momentum distribution of a captured pion is restricted by the maximum angular momentum deduced from the product of the atomic distance and the maximum linear momentum of the captured pion. (orig.)