Mobile UHV set-up for the investigation of electron spectra at large accelerators:: First results on high charge effects

We measured energy spectra of electrons from sputter cleaned amorphous carbon targets induced by swift ions of constant velocity (E-p/M-p = 9 MeV/u) with a new mobile ultra high vacuum set-up designed for large scale accelerators. We varied the projectile charge q(p) from 6 to 27. The shape of the spectra was found to depend strongly on q(p): a q(p)(2) scaling law at large electron energies and a strong saturation with increasing q(p) for low energy electrons (below the 1 s ionization threshold) are observed. We also observed an additional feature on the high energy side of the KLL Auger peak, for large projectile charges only. This additional peak may be interpreted as a hypersatellite line due to the double ionization of the K shell. (C) 1998 Elsevier Science B.V. All rights reserved.