PENNING-TRAP MASS MEASUREMENTS OF NEUTRON-DEFICIENT RB AND SR ISOTOPES

The Penning-trap mass spectrometer ISOLTRAP installed at the on-line m ass separator ISOLDE 2 at CERN has been used for mass determination of Rb-75-87 and Sr-78-83,Sr-87. Ions are captured in a Penning trap and their cyclotron frequency Omega(c) = (q/m)B in the trapping field B is measured. Ratios of these frequencies lead to the determination of th e atomic mass of these isotopes. A resolving power of typically m/Delt a m approximate to 10(6) and an accuracy of delta m = 10 keV is obtain ed. The mass of Sr-78 is measured for the first time and, in most case s, the mass values of the other isotopes are significantly improved. T he experimental masses are compared with theoretical predictions.