H0(N=3,4) STARK STATES PRODUCED IN THE INTERACTION OF 800-MEV H- IONS WITHTHIN FOILS

The interaction of 800-MeV ${\mathrm{H}}^{\mathrm{\ensuremath{-}}}$ ions with a thin foil produces protons, the ground state and excited states of neutral ${\mathrm{H}}^{0}$ atoms, and unstripped ${\mathrm{H}}^{\mathrm{\ensuremath{-}}}$ ions. We investigated the distributions of individual ${\mathrm{H}}^{0}$ Stark states within the $n=3$ and 4 levels produced by C and ${\mathrm{Al}}_{2}{\mathrm{O}}_{3}$ foil stripping of ${\mathrm{H}}^{\mathrm{\ensuremath{-}}}$ ions. Foils of various thicknesses were placed upstream of a magnet with a linearly increasing transverse field along the beam direction producing a motional electric field strong enough to ionize ${\mathrm{H}}^{0}$ states with $ng~3.$ We consider three questions: (i) What are the populations of individual ${\mathrm{H}}^{0}$ Stark states produced in the interaction of 800-MeV ${\mathrm{H}}^{\mathrm{\ensuremath{-}}}$ ions with thin C and ${\mathrm{Al}}_{2}{\mathrm{O}}_{3}$ foils, (ii) how do the relative population distributions change with foil thickness, and (iii) how is the population distribution produced in an ${\mathrm{Al}}_{2}{\mathrm{O}}_{3}$ foil modified when the foil is placed in a magnetic field? A simple qualitative model is presented to explain the major trends.