ANGULAR-DISTRIBUTION OF DELTA-ELECTRONS EMITTED IN COLLISIONS OF 1.0-MEV U F(Q+) (Q=4, 6, 8, 9) WITH MOLECULAR-HYDROGEN/

The angular distribution, as well as the energy distribution of delta electrons produced in collisions of 1.0-MeV/u F(q+) (q = 4,6,8,9) ions with molecular hydrogen, have been studied for laboratory observation angles (theta(L)) from 0-degrees to 70-degrees with respect to the be am direction. The measurements are in fair agreement with the impulse approximation calculations which use the quantal elastic electron-ion differential scattering cross sections folded with the Compton profile of the target electrons. We observe that the energy of the centroid o f the binary-encounter-electron (BEE) peak is projectile charge state, q, and laboratory angle, theta(L), dependent. Moreover, at 0-degrees, an enhancement of the ratio of the observed double differential cross section for nonbare projectiles to that for the bare ion projectiles, sigma(q+)/sigma(9+), is observed, contrary to the q2 scaling predicte d by a first Born calculation for ionization. This ratio sigma(q+)/sig ma(9+) decreases monotonically with increasing theta(L), and becomes s maller than one for theta(L) greater-than-or-equal-to 30-degrees.