High-accuracy mass determination of unstable nuclei with a Penning trap mass spectrometer

The mass of a nucleus is its most fundamental property. A systematic study of nuclear masses as a function of neutron and proton number allows the observation of collective and single-particle effects in nuclear structure. Accurate mass data are the most basic test of nuclear models and are essential for their improvement. This is especially important for the astrophysical study of nuclear synthesis. In order to achieve the required high accuracy, the mass of ions captured in a Penning trap is determined via their cyclotron frequency $ \nu _{c} $. Mass measurements already performed with this technique at ISOLDE-2 demonstrated that resolving powers exceeding $ \nu _{c} / \Delta \nu _{c} $ (FWHM) of 1~million can easily be achieved and accuracies of typically $ \Delta m / m \approx 10^{-7} $ are obtained. The technique can be applied to isotopes of all elements available at ISOLDE. Hence a highly accurate, systematic investigation of nearly the complete nuclear mass surface becomes possible.