Outer Shell Projectile Ionization in Very Fast Heavy Ion Collisions

Abstract

The new heavy-ion accelerator VICKSI in Berlin makes possible the study of ionization processes in very fast heavy-ion collisions. In this paper we report measurements of secondary electrons with energies up to 7 keV produced in collisions of 60 MeV to 200 MeV Ne-ion projectiles with a neon gas target. A typical feature of the electron spectra is a pronounced peak, usually called an electron loss peak (ELP). The ELP is caused by the emission of projectile electrons during the collision. It was first systematically examined by Wilson and Toburen¹ and by Burch et al². We have examined the dependence of the ELP on projectile energy, on projectile charge-state and on observation angle. The results are presented and compared with two alternative calculations in which different forms of the binary-encounter approximation^3,4 are used.