Muonic cascades in isolated low-Z atoms and molecules

Muonic x-ray cascades in B, C, N, O, and Ne following muonic atom formation in B2H6, CH4, C2H6, C4H10, N-2, O-2, and Ne were investigated. The densiti es 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 at oms or molecules during the cascade. Using semiconductor detectors, the yie lds 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 variati on of only two parameters: the number of electrons and the muon angular mom entum distribution at the starting point of the calculation. The cascade of mu Ne formed in monoatomic neon was described best. Moreover, muonic carbo n cascades were found to differ according to the sort of hydrocarbon, demon strating the influence of the capturing molecule's structure on the muonic cascade. By varying the number of initially available electrons, the molecu lar effects could be described with the cascade program. [S1050-2947(99)020 05-3].