Energy Dependence of the Total Cross Section for He-He Collisions from 0.30 to 3.00 keV

Abstract

The total cross section for scattering of He by He is measured at 100-eV intervals in an energy range from 0.30 to 3.00 keV. Measurements are made using detector angular resolutions of 0.056° and 0.260°. The cross section is found to decrease monotonically from 12.5 to 5.0 ${\mathrm{\AA }}^2$ and from 7.0 to 2.6 ${\mathrm{\AA }}^2$, respectively, as the energy increases. Small-angle differential measurements are also made out to scattering angles of 1.25° at incident energies of 1.80 and 3.00 keV. At 3.00 keV a ${\mathrm{He}}^{+}$ signal is found at sacttering angles beyond 0.8°. The ratio of the ion to the total signal increases to about 10% at 1.25°. The total-cross-section data are used to infer a potential.