The velocity filter SHIP, performance and survey of current experiments

Abstract The velocity filter SHIP is used to investigate unslowed evaporation residues from heavy ion fusion reactions. The main subjects of investigation are α emitting and spontaneously fissioning nuclei very far from stability with halflives as short as microseconds and formation cross-section down to the nanobarn region. The efficiency of the filter is calculated by a Monte Carlo method taking into account momentum transfer from nucleons and α particles evaporated from the excited compound system as well as energy loss, scattering in the target, and the ionic charge distribution. The calculations are compared with experimental results. For the irradiation of low melting point targets with high beam currents a rotating target wheel has been developed. Light evaporation residues are identified by an ionisation chamber. α emitting and spontaneously fissioning nuclei are investigated by implantation into surface barrier detectors. The high background rejection and sensitivity of detection are demonstrated for the case of the identification of Fm and element 104.