Charge-changing cross sections forH−ions incident on a Na vapor target

Measurements are reported for the total charge-changing cross sections ${\sigma }_{-0\mathrm{}}$ for 1-25-keV ${\mathrm{H}}^{-}$ ions incident on a Na vapor target and ${\sigma }_{-+}$ for 7.5-25-keV ${\mathrm{H}}^{-}$ ions incident on a Na vapor target. The cross section ${\sigma }_{-0\mathrm{}}$ is 4.2 × ${10}^{-15\mathrm{}}$ ${\mathrm{cm}}^2$ at 1 keV and falls monotonically to 1.5 × ${10}^{-15\mathrm{}}$ ${\mathrm{cm}}^2$ at 25 keV. The cross section ${\sigma }_{-+}$ is 9 × ${10}^{-18\mathrm{}}$ ${\mathrm{cm}}^2$ at 7.5 keV and rises to 4.0 × ${10}^{-17\mathrm{}}$ ${\mathrm{cm}}^2$ at 25 keV.