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HK: Fachverband Physik der Hadronen und Kerne

HK 14: Structure and Dynamics of Nuclei V

HK 14.1: Gruppenbericht

Dienstag, 11. März 2025, 14:00–14:30, HS 2 Physik

Key observables for quadrupole collectivity in N=80 isotones — •H. Mayr¹, T. Stetz¹, V. Werner¹, U. Ahmed¹, K. Gladnishki², K.E. Ide¹, D. Kocheva², C.M. Nickel¹, N. Pietralla¹, G. Rainovski², and R. Zidarova¹ — ¹TU Darmstadt, Germany — ²Sofia University, Bulgaria

Quadrupole collectivity near shell closures dominates the structure of low-lying excited states. Predominantly of one-quadrupole phonon character are the isoscalar proton-neutron symmetric 2₁⁺ state and the isovector mixed-symmetry 2_1, ms⁺ state. Due to strong fragmentation of the 2_1, ms⁺ state of ¹³⁸Ce, the underlying shell structure [1] spreads the M1 transition strength to the 2₁⁺ state over several 2⁺ states. This key feature of the 2_1, ms⁺ state is concentrated in a single 2⁺ state in nuclei below the π g_7/2 subshell closure [2,3]. This finding is supported by recently obtained B(M1,2_2,3⁺→2₁⁺) strengths of ¹³²Te [4]. Shell stabilisation in the heavier N=80 isotones is restored in the π d_5/2 subshell [5,6]. With other key observables like the B_4/2 ratio, a comprehensive picture of quadrupole collectivity in the N=80 isotones will be drawn.

[1] G. Rainovski et al., Phys. Rev. Lett. 96 (2006) 122501

[2] T. Ahn et al., Phys. Lett. B 679 (2009) 1

[3] N. Pietralla et al., Phys. Rev. C 58 (1998) 796

[4] T. Stetz et al., Submitted to Phys. Rev. C

[5] R. Kern et al., Phys. Rev. C 102 (2020) 041304

[6] T. Stetz et al., Submission in preparation

*Supported by the BMBF under grant numbers 05P21RDCI2 and 05P24RD3.

Keywords: mixed-symmetry; lifetime