No abstract

Muonic x-ray cascades in B, C, N, O, and Ne following muonic atom formation in B 2 H 6 , CH 4 , C 2 H 6 , C 4 H 10 , N 2 , 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 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. ͓S1050-2947͑99͒02005-3͔

Diffusion of muonic deuterium d and muonic hydrogen p atoms produced following the stopping of negative muons in D 2 or H 2 at 300 K was studied at pressures of 47-750 mbar ͑H 2 ) and 94-1520 mbar ͑D 2 ) in two distinct target geometries. Time intervals were recorded between entry of negative muons into the gas and arrival of each resulting d or p atom at one of 50 foils immersed in the gas, and spaced regularly along the muon beam axis. The results of such measurements were fitted to time distributions generated by Monte Carlo methods, using theoretical scattering predictions and empirically chosen forms for the initial energy distributions of the muonic atoms in the 1S state. Results indicate muonic atom energy distributions which ͑a͒ are different for d and p and ͑b͒ vary with pressure. The best-fit energy distributions have mean energies ranging from 1.5 eV for d at 94 mbar to у9 eV for p at 750 mbar. The data are also sensitive to scattering cross sections for d and p, and are consistent with current theoretical calculations for the dϩD 2 cross sections. In the case of pϩH 2 scattering, the experimental data suggest discrepancies with the theoretical predictions.