Ionization of FastHe0in the Triplet Metastable State

Cross sections have been measured for production of ${\mathrm{He}}^{+}$ ions by the collision of 10- to 30-keV ${\mathrm{He}}^0$ atoms in the triplet metastable state with target atoms of Xe, Kr, ${\mathrm{H}}_2$, ${\mathrm{N}}_2$, Ar, Ne, and He. Fast ${\mathrm{He}}^0$ atoms are produced in the first of two gas targets in which various neutralizer gases may be present at low density. The fractions of ${\mathrm{He}}^0$ produced in the triplet metastable state in these various neutralizer gases are known. The fraction of fast ${\mathrm{He}}^{+}$ emerging from a second target containing Xe, Kr, ${\mathrm{H}}_2$, ${\mathrm{N}}_2$, Ar, Ne, or He is analyzed as a function of the density of the second gas target, and the cross sections for ionization of ${\mathrm{He}}^0$ atoms from the metastable triplet state are determined. Typical values of the cross sections at 30 keV are 110±40, 37±17, 122±58, 86±42, 18±12, and 65±31 in units of ${10}^{-17\mathrm{}}$ ${\mathrm{cm}}^2$ for gas targets of Xe, Kr, ${\mathrm{H}}_2$, ${\mathrm{N}}_2$, Ar, Ne, and He, respectively.