Experimental investigation of fission fragment and alpha-recoil induced ejection of secondary ions

Abstract

Secondary ions released from solid surfaces by fision fragments of 252Cf or by α-recoil particles were studied with an improved time-of-flight mass spectrometer providing a mass resolution of ca. 2500. Firstly, we investigated the emission of secondary ions from insulators covered by a very thin metallic layer. At bombarding energies of ca. 100 MeV ion explosion spikes were expected to set in at a metallic surface coverage below 100 Å thickness. However, no substantial differences of yields were observed for 10–1000 Å Cr-films evaporated on Mylar. Secondly mass spectra and energy distributions of ions ejected by ca. 80 keV and ca. 100 MeV particles were studied. In both cases radioactive sources provided the bombarding particles. We used α-recoil nuclei from 241Am and fission fragments from 252Cf. The comparison of the mass spectra shows clearly, that the energy transfer to secondary ions is considerably higher at 80 keV bombarding energy.