Mass Measurements Of Exotic Nuclides At Shiptrap

The Penning trap mass spectrometer SHIPTRAP is installed behind the velocity-filter SHIP at GSI for high-precision mass measurements of fusion-evaporation residues. To facilitate an efficient stopping of the reaction products a buffer gas stopping cell is utilized, In an investigation of neutron-deficient nuclides in the terbium-to-thulium region around A;7 146, 18 new or improved mass values have been obtained, resulting in a more accurate determination of the proton drip line for holmium and thulium. With the present performance of SHIPTRAP, a first direct mass measurement of transuranium elements in the nobelium region is within reach.