Double-electron detachment cross sections for 5-45 keV H- ions incident on he atoms

The authors report absolute measurements of double-electron detachment cross sections for 5-45 keV H- ions incident on He atoms. The measurements are made using a new negative-ion accelerator at the University of Toledo. The cross sections are determined by measuring the rate of growth of the H+ ion current exiting a He target, as a function of increasing He target density. The cross section increases from a value of 4.0 X 10-17 cm2 at an impact energy of 5 keV to a value of 5.3 X 10-17 cm2 at 12.5 keV. Above 12.5 keV, the cross section falls to a value of 3.6 X 10-17 cm2 at 45 KeV. These values of the cross section are compared with previous measurements of the double-electron detachment cross section for H- ions incident on He atoms