PhD ceremony: Direct mass measurements of No, Lr and Rf isotopes with SHIPTRAP and developments for chemical isobaric separation | Brankica Anđelić

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Abstract

This thesis presents high-precision mass measurements of the heaviest nuclides performed with the Penning-trap mass spectrometer SHIPTRAP and technical developments directed towards studies of medium-heavy neutron-deficient isotopes in the region around Sn-100. Direct mass measurements of these exotic nuclei provide important quantities, such as nucleon separation energies, which are used to study the nuclear structure and the synthesis of different chemical elements through nucleon-capture processes.

Within this work, high-precision mass spectrometry of No-251, No-254 (Z=102) and Lr-254, Lr-255, Lr-256 (Z=103) was performed at SHIPTRAP by employing the PI-ICR (Phase-Imaging Ion-Cyclotron-Resonance) technique. For the first time, the atomic ground-state masses of the odd-A isotope No-251 and the odd-odd isotope Lr-254 have been measured directly with a precision on the order of 10E−8. Also, the ground-state mass of the superheavy nucleus Rf-257 was determined for the first time. These results are used to benchmark atomic mass models in the vicinity of the deformed neutron shell closure at N=152 and they will indirectly improve the atomic masses of isotopes up to the element darmstadtium (Z=110). The latter will contribute to the investigation of the strength of the shell closure at N=162.

In addition, a novel chemical separation technique is proposed to separate Sn-100 from its isobars by taking advantage of gas-phase chemistry inside a gas catcher. The gas catcher has been designed and it will be used as a part of the CISE (Chemical Isobaric Separation) setup to systematically study the gas-phase chemistry.

Dissertation: http://hdl.handle.net/11370/c804f2a7-38f1-48c4-8e8a-226e64afeec2