Muonic cascades in isolated low-<b><i>Z</i></b>atoms and molecules

Abstract

Muonic x-ray cascades in B, C, N, O, and Ne following muonic atom formation in ${\mathrm{B}}_{2}{\mathrm{H}}_{6},$ ${\mathrm{CH}}_{4},$ ${\mathrm{C}}_{2}{\mathrm{H}}_{6},$ ${\mathrm{C}}_{4}{\mathrm{H}}_{10},$ ${\mathrm{N}}_{2},$ ${\mathrm{O}}_{2}$, and Ne were investigated. The densities of the different target gases were low enough to prevent any contact of the atom or molecule on which the formation takes place with surrounding atoms or molecules during the cascade. Using semiconductor detectors, the yields of transitions in several series with energies between 1.5 keV and 300 keV were measured. Cascade calculations were performed in order to explain the observed transition yields. The cascades could be reproduced by variation of only two parameters: the number of electrons and the muon angular momentum distribution at the starting point of the calculation. The cascade of $\ensuremath{\mu}\mathrm{Ne}$ formed in monoatomic neon was described best. Moreover, muonic carbon cascades were found to differ according to the sort of hydrocarbon, demonstrating the influence of the capturing molecule's structure on the muonic cascade. By varying the number of initially available electrons, the molecular effects could be described with the cascade program.