Optimization studies of the CERN-ISOLDE neutron converter and fission target system

The ISOLDE facility at CERN has been one of the leading isotope separator on-line (ISOL) facilities worldwide since it became operative in 1967. More than 1000 isotopes are available at ISOLDE, produced after the bombardment of various primary targets with a pulsed proton beam of energy 1.4 GeV and an average intensity of 2 muA. A tungsten solid neutron converter has been used for ten years to produce neutron-rich fission fragments in UC(x) targets. In this work, the Monte Carlo code FLUKA and the cross-section codes TALYS and ABRABLA were used to study the current layout of the neutron converter and fission target system of the ISOLDE facility. An optimized target system layout is proposed, which maximizes the production of neutron-rich isotopes and reduces the contamination by undesired neutron-deficient isobars. The studies here reported can already be applied to ISOLDE and will be of special relevance for the future facilities HIE-ISOLDE and EURISOL.