K-K electron capture cross sections for 0.4 to 1.5 MeV 11H+ and to 2.0 MeV 24He+ projectiles incident on gaseous CH4 targets

The ratio of the cross section for K-K electron capture to the total K-vacancy production cross section is measured by an electron-ion time-of-flight coincidence technique for 0.4 to 1.5 MeV 11H+ and 1.0 to 2.0 MeV24He+ projectiles under single collision conditions with gaseous CH4 targets. Electron capture cross sections were determined by multiplying the measured ratios by the total K-vacancy production cross sections which were measured in a separate experiment. In that experiment the integrated yield per incident projectile in the Auger-electron-peak for 0.6 MeV 11H+ projectiles was normalized to 9.54 x 10-19 cm2, the absolute cross section of Stolterfoht and Schneider. The total K-vacancy production cross sections on this absolute scale were used to extract the electron capture cross sections reported here. (orig.)