Universität zu Köln

Droste, Maximilian Paul ORCID: 0000-0002-0846-8113 (2026). Nuclear Structure and Collectivity of Neutron-Rich Tin Isotopes around 132Sn. PhD thesis, Universität zu Köln.

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Abstract

The collective properties of the even–even neighbors of the doubly magic nucleus 132Sn were investigated through a series of safe Coulomb-excitation experiments. The aim of this work was to obtain reliable information on the first excited 2+ states in 130Sn and 134Sn, which provide sensitive experimental insigth for the evolution of quadrupole collectivity near the Z = 50, N = 82 shell closure. Four experimental campaigns were conducted between November 2022 and October 2025 at the HIE-ISOLDE facility at CERN, using post-accelerated radioactive ion beams at 4.4 MeV/u incident on 206Pb and 194Pt targets. De-exciting γ rays were detected with the Miniball spectrometer in coincidence with scattered particles, enabling a clean selection of Coulomb-excited events. From these data, B(E2; 0+→ 2+) values of 0.0486(57) and 0.0449(57) e2b2 were extracted for 130Sn and 134Sn, respectively. These results represent the most precise determinations to date and resolve discrepancies between earlier experimental studies and theoretical predictions. In the context of the isotopic chain, the new values confirm the enhanced B(E2) strength at 132Sn and provide consistent evidence for a local maximum of collectivity at the doubly magic nucleus. The spectroscopic quadrupole moments of the 2+ 1 states in 130Sn and 134Sn were found to be compatible with zero within uncertainties, supporting a near-spherical structure of nuclei adjacent to the 132Sn core. The presented results deliver well-constrained experimental benchmarks for large-scale shell-model calculations employing realistic interactions and contribute to a more coherent understanding of quadrupole collectivity and shell evolution in the Z = 50 region while also proving the sphericity and double-magic properties of 132Sn.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Droste, Maximilian Paul mdroste@ikp.uni-koeln.de https://orcid.org/0000-0002-0846-8113 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-809221
Date:	2026
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Physics > Institute for Nuclear Physics
Subjects:	Physics
Uncontrolled Keywords:	Keywords Language Nuclear Strucutre UNSPECIFIED Doubly-magic nuclei UNSPECIFIED Collectivity UNSPECIFIED
Date of oral exam:	18 May 2026
Referee:	Name Academic Title Reiter, Peter Prof. Dr. Wimmer, Kathrin Prof. Dr. Herzberg, Rolf-Dietmar Prof. Dr.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/80922