On the μ-mesonic atoms

Abstract

In an attempt to get a deeper insight into the problem of the « missing X-rays » in the capture ofμ-mesons in the light elements, a complete cascade calculation of theμ-meson transitions in the mesonic atom was conducted. The results indicate again that the calculatedK X-ray yields belowZ=6 and theL X-ray yields belowZ=14 are much above the experimental values. As was noted before by other authors, the deficiency of X-rays increases linearly with decreasing quantum energy between about 90 keV and 20 keV. The experimental yields agree with the calculations above 90 keV, and are lower than the calculated values, by a factor of about 5, at 20 keV. Good agreement between the calculations and experiment is obtained, however, for the (approximately energy-independent) ratios of the higher to basic X-ray yields, provided that a proper choice of the initial meson distribution is made. A comparison between the calculated Auger electron yields and the experimental results forμ−-capture in nuclear emulsions seems to indicate that the « mixed » Auger-radiative transitions introduced by Ruderman are indeed effective (apparently close to 100%) in the de-excitation of the metastable 2s level in CNO. If this mixed transitions play the same role also in the lightest elements (Li, Be, B), the problem of the « missing » X-rays becomes more serious than before. The expected Auger electron spectrum forμ−-capture in the heavy elements (AgBr) of nuclear emulsion has also been calculated.