Köln 2025 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 26: Structure and Dynamics of Nuclei VII
HK 26.2: Talk
Wednesday, March 12, 2025, 14:30–14:45, HS 2 Physik
Study of the spin-flip orbitals in N = 83 isotones with lifetime measurement via (n, gamma) reactions — •zhiqiang chen1, kathrin wimmer1, elisa maria gandolfo1, martha reece1, wiktor poklepa1, caterina michelagnoli2, jean michel daugas2, lorenzo domenichetti2, and zhihuan li3 — 1GSI, Darmstadt, Germany — 2ILL, Grenoble, France — 3PKU, Beijing, China
The spin-orbit (SO) splitting is closely linked to nuclear shell gaps and magic numbers. This splitting can be significantly reduced in exotic nuclei with extreme N/Z ratios, a phenomenon that remains poorly understood. The energies of the spin-flip ν p1/2 and ν p3/2 orbitals above the N = 82 shell closure are still not well established. Astonishingly, even in nuclei close to stability the ν p1/2 and ν p3/2 orbitals are not well characterized.
To achieve a comprehensive understanding of the SO splitting between the ν p1/2 and ν p3/2 orbitals in N = 83 isotones, a thermal neutron capture experiment was conducted at the Institut Laue-Langevin (ILL), Grenoble. γ-rays from (n, γ) reaction were measured using a new HPGe array, comprising eight FIPPS Clover and eight IFIN-HH Clover detectors. Properties of the ν p1/2 and ν p3/2 orbitals in 139Ba83 and 141Ce83 will be characterized by deriving the B(M1; 1/2− → 3/2−) values. This involves determining the mixing ratio δ(M1/E2) through γ-γ angular correlations and the lifetimes of the 1/2− states using the Gamma Ray Induced Doppler Shift Attenuation method. In this talk, I will present some preliminary results on the lifetime measurements of low-lying states in 139Ba83 and 141Ce83.
Keywords: spin-orbital splitting; (n, gamma) reaction; lifetime measurement