We present experimental evidence for a deceleration of convoy electrons produced by 5 MeV/u ions (N⁷⁺, Ne¹⁰⁺, S¹³⁺, Ni²³⁺, and Ag³⁷⁺) during the interaction with insulator foils at normal incidence. The deceleration first increases with increasing projectile charge, reaches a maximum at a projectile charge of about 16, and seems to approach zero for even higher charges. Different possible mechanisms and quantitative estimates for the slowing down of convoy electrons are presented.
Physical Review Letters. Woodbury. Vol. 79, n. 10 (Sept. 1997), p. 1821-1824