The cross sections for the double ionization, ionization plus excitation, and double excitation of H2 by electrons and protons in the range of 350 to 3500 keV/amu have been measured. In all cases, the cross section for electron bombardment was greater than that for equivelocity proton bombardment. The results are discussed in terms of first and second Born processes and interferences between the two.

The singleand double-ionization cross sections of H& produced by fast-electron bombardment have been measured. The electrons had selected energies between 750 and 3500 keV/amu. The results are compared to previously reported data from this laboratory for equivelocity protons on H2.The ratio R of double-to-single-ionization cross sections is about a factor of 2 greater for electrons than for protons. The difrerenee occurs because of differences in both the single-and doubleionization cross sections. At 750 keV/amu, the single-ionization cross section produced by electrons is 0.8320.04 times that produced by protons. At the same velocity, the double-ionization cross section produced by electrons is 2.25+0.35 times that produced by protons. The results from the H2 target are compared to results from a helium target, and marked similarities are observed.

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