Direct high-precision mass spectrometry of superheavy elements with SHIPTRAP

Abstract

Direct mass measurements in the region of the heaviest elements were performed with the Penning-trap mass spectrometer SHIPTRAP at GSI Darmstadt. Utilizing the phase-imaging ion-cyclotron-resonance massspectrometry technique, the atomic masses of 251No (Z = 102), 254Lr (Z = 103), and 257Rf (Z = 104) available at rates down to one detected ion per day were determined directly for the first time. The ground-state masses of 254No and 255,256Lr were improved by more than one order of magnitude. Relative statistical uncertainties as low as δm/m ≈ 10−9 were achieved. Mass resolving powers of 11 000 000 allowed resolving long-lived low-lying isomeric states from their respective ground states in 251,254No and 254,255Lr. This provided an unambiguous determination of the binding energies for odd-A and odd-odd nuclides previously determined only indirectly from decay spectroscopy.