Double-Electron-Capture Cross Sections for Incident Protons in the Energy Range 75 to 250 keV

Abstract

The double-electron-capture cross sections were measured for protons in the energy range from 75 to 250 keV incident upon the target gases ${\mathrm{H}}_{2}$, He, Ar, Kr, ${\mathrm{N}}_{2}$, and ${\mathrm{H}}_{2}$O. A power law extrapolation of the present results for ${\mathrm{H}}_{2}$ and He joins smoothly with previously measured cross sections at higher- and lower-impact energies; however, wide discrepancies exist between measured and calculated cross section values. For the heavier target gases, a power law extrapolation of the present results is in disagreement with previous measurements. This disagreement is attributed to the power law being inappropriate at energies where electron capture from inner electron shells is possible.