Decay studies and mass measurements on isobarically pure neutron-rich Hg and Tl isotopes

We propose to perform mass measurements followed by �- and -decay studies on isobarically pure beams of neutron-rich Hg and Tl isotopes, which are very poorly known due to a large contamination at ISOL-facilities with surface-ionised francium. The aim is to study the binding energies of mother Hg and Tl nuclides, as well as the energies, spins and parities of the excited and ground states in the daughter Tl and Pb isotopes. The proposed studies will address a new subsection of the nuclear chart, with Z 126, where only 9 nuclides have been observed so far. Our studies will provide valuable input for mass models and shell-model calculations: they will probe the proton hole-neutron interaction and will allow to refine the matrix elements for the two-body residual interaction. Furthermore, they also give prospects for discovering new isomeric states or even new isotopes, for which the half-lives are predicted in the minute- and second-range. To reach the isobaric purity, the experiments will be performed at the ISOLTRAP setup. The mass measurements will take place in the precision Penning trap, which – for excitation energies of 100 keV or more – can even resolve isomers. The decay system will be located behind ISOLTRAP, where the mother nuclei will be implanted in a tape surrounded by detectors measuring the intensity, energy and time evolution of the emitted � and radiation.