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Abstract

Atomic masses and hence binding energies of nuclides are of great importance for studies of nuclear structure since they reflect all effective interactions in a nucleus. Within this thesis the masses of seven nuclides, namely 194Au, 194Hg, 190,193,198Tl and 202,208Pb, were determined at the Penning-trap mass spectrometer ISOLTRAP at ISOLDE/CERN. The thallium region in the chart of isotopes is of special interest due to the occurrence of nuclear structure effects like low-lying isomers, level inversion, shape coexistence and deformations. These effects are investigated by applying finite-difference mass formulas, such as the two-neutron separation energies or the so-called empirical pairing gaps. The second topic addressed within the present thesis is an ultra-stable voltage source, called StaReP (Stable Reference for Penning Trap Experiments), which was developed at the Max-Planck-Institut für Kernphysik. It is one of the key components of the high-precision mass spectrometer PENTATRAP, containing a tower of five Penning traps. A 25-channel voltage source with a relative stability of few 10^−8 over a period of 10 minutes in the range of 0 to −100V is mandatory for PENTATRAP aiming for mass measurements with relative mass uncertainties of ≤ 10^−11. Mass values with such a high precision allow for stringent tests of quantum electrodynamics in strong electric fields, testing Einstein’s mass-energy relation E = mc^2 as well as measurements of decay energies (Q-values) with applications in neutrino physics.