Measurements of cross sections for electron detachment from H⁻ions by proton impact

An apparatus is described in which two beams intersect at an angle of 8 1 / 2 degrees so that interactions between ions can be studied. The formation of hydrogen atoms from H - ions by proton impact has been investigated for barycentric energies between 1.49 and 35.2 keV. Cross sections which were previously measured for the mutual neutralization of H + and H - were then subtracted from these results to obtain cross sections for proton impact detachment. These attained a maximum value of 4.4*10 -15 cm 2 at 10 keV, which is two orders smaller than the theoretical prediction of Gayet et al. (1973), but agrees well, above 18 keV, with measured electron impact cross sections scaled to the same interaction speeds.