Cross sections for electron capture by protons have been measured at energies from 440 keV to 13.8 MeV in ${\mathrm{N}}_2$ and in Ar; to 5.41 MeV in He; and to 2.45 MeV in ${\mathrm{H}}_2$. Electron-loss cross sections in the same gases at 1.027 and 2.44 MeV are also presented. The measurements were carried out by analysis of particle-beam composition after exit from a gas target of known composition and thickness. The beam was separated magnetically, and the charged and neutral components were detected by a Faraday cup and a scintillator, respectively. The energy range of our results overlaps that of Barnett and Reynolds between 440 keV and 1 MeV. Our electron-capture cross sections in this region agree within the experimental uncertainty for ${\mathrm{H}}_2$ and He, but are larger by up to 50% in ${\mathrm{N}}_2$ and Ar.

• Received 13 January 1967

DOI:https://doi.org/10.1103/PhysRev.158.85