Beta-decay energies and masses of short-lived isotopes of rubidium, caesium, francium, and radium

Total decay energies have been measured for a number of neutron- deficient Rb and Cs isotopes, as well as for some neutron-rich isotopes of Fr and Ra. Mass separated sources were produced at the ISOLDE on-line separator at CERN. By applying two different beta - gamma coincidence methods, Q values or their lower limits were determined for /sup 76-78/Rb, /sup 80/Rb, /sup 121-124/Cs, /sup 222 /Fr, /sup 224-226/Fr, /sup 229/Ra and /sup 229/Ac. For many of these nuclei, the atomic mass excesses could be derived, allowing the comparison of masses of far unstable nuclei with predictions from mass formulae. The odd-odd nuclei /sup 76/Rb and /sup 78/Rb appear to be 1-1/sup 1///sub 2/ MeV more strongly bound than expected from the systematics. (70 refs)