Heavy-ion-induced electron emission from thin carbon foils

We have measured heavy-ion-induced (5≤${\mathit{Z}}_{\mathit{p}}$≤26; 0.3ES have the same velocity dependence. Similar to proton bombardment for heavy ions, we also observe a maximum of the yield of electron emission at energies very close to the stopping-power maximum. A systematic study of the ratio Λ=γ/S with the projectile atomic number ${\mathit{Z}}_{\mathit{p}}$ reveals a nonequilibrium regime for 1${\mathit{Z}}_{\mathit{p}}$${\mathit{Z}}_{\mathit{p}}$) and an equilibrium regime for ${\mathit{Z}}_{\mathit{p}}$≥6 ions (Λ independent of ${\mathit{Z}}_{\mathit{p}}$). The obtained results are discussed in the framework of an extended Sternglass-type model, taking into account nonequilibrium projectile energy losses near the exit and entrance surfaces of the carbon foils.