Abstract
Very neutron-deficient francium and radium isotopes have been produced in fusion evaporation reactions using and ions on targets and ions on targets. The gas-filled recoil separator RITU was employed to collect the fusion products and to separate them from the scattered beam. The activities were implanted into a position-sensitive silicon detector after passing through a gas-counter system. The isotopes were identified using spatial and time correlations between the implants and decays. Two new α decaying radium isotopes, and , were identified. The α decay energy and half-life of were measured with improved precision. The α decay properties measured for the francium isotopes , and were confirmed, in many cases with improved precision. For the first time, a proton intruder state was identified in francium isotopes, namely in and tentatively in . The measured decay properties for the neutron-deficient odd-mass Fr isotopes suggest an onset of substantial deformation at .
1 More- Received 27 October 2004
DOI:https://doi.org/10.1103/PhysRevC.71.024306
©2005 American Physical Society