TRANSPORT OF ELECTRONS INDUCED BY HIGHLY-CHARGED NI (74 MEV U) AND CU(9.6 MEV/U) IONS IN CARBON - A STUDY OF TARGET-THICKNESS-DEPENDENT ELECTRON YIELDS/

We investigated the transport of heavy-ion-induced electrons in solids by both experiment and numerical simulation. We measured electron yie lds from the beam entrance and exit surfaces of thin carbon foils (d a pproximate to 3 mu g/cm(2)-50 mg/cm(2)) bombarded with swift, highly c harged Cu-q+ (q = 25-28 and E(p) = 9.6 MeV/u) and Ni-q+ (q = 26, 28 an d E(p) = 74 MeV/u) ions. We obtained the transport lengths of high-ene rgy (E greater than or similar to 100 eV) electrons and diffusion leng ths of slow electrons (E less than or similar to 100 eV) and deduced a mean energy of the ejected electrons (approximate to 1 keV at 10 MeV/ u and approximate to 8 keV at 74 MeV/u). The high-energy electrons rep resent a fraction of 15-20% of the total electron yields at 9.6 MeV/u, but up to 35% at 74 MeV/u. We show that backscattering of fast, forwa rd-emitted electrons towards the beam entrance surface cannot be negle cted in fast-ion-induced electron emission. The experimental results a re used as a benchmark for the improvement of our numerical simulation of the primary stage of the ion-matter interaction.