Indications for a new electron-ejection mechanism: Nuclear-track guided electrons induced by fast heavy ions in insulators

Abstract Convoy-electron emission has been investigated experimentally and theoretically for heavy-ion irradiation of conducting and insulating solid-state targets at a particle velocity of 14.1 a.u. (5 MeV/u). We present experimental evidence for a deceleration of convoy electrons produced by N 7+ , Ne 10+ , S 13+ , Ni 23+ and Ag 37+ ions 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. It is proposed that there is a significant fraction of nuclear-track guided electrons emitted close to the convoy-electron velocity. The high ionization density inside the solid leads to an attractive potential that may guide electrons along the track, similar to the particle motion under channeling conditions.