Excitation of Swift Heavy Ions in Foil Targets: Visible Radiation from Fe, Ni and Cu

Abstract

Studies have been made of visible radiation from highly stripped 100-144 MeV Fe, Ni and Cu ions excited by transmission through thin carbon foils. All the observed transitions in the region 180-530 nm were identified with hydrogenic transitions of An = 1 or 2, in charge states between 14 and 22. Light intensities observed are proportional to the outgoing beam charge-state distributions. For thin foils « 20 Ilgcm- 2 ) the light output is less than that from beams in charge equilibrium. It is shown that these observations are consistent with a surface excitation mechanism that depends on the prior formation of multiply excited ions in the solid target.