Bonn 2020 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 45: Structure and Dynamics of Nuclei VIII

HK 45.1: Group Report

Thursday, April 2, 2020, 14:00–14:30, J-HS E

High-spin structures of transitional Xe and Ba nuclei in the 50 ≤ Z, N ≤ 82 region — •L. Kaya¹, A. Vogt¹, P. Reiter¹, M. Siciliano^2,3, and A. Gargano⁴ — ¹IKP, Universität zu Köln — ²INFN - LNL, Italy — ³INFN Padova, Italy — ⁴INFN Napoli, Italy

The 50 ≤ Z, N ≤ 82 region is a fertile testing ground for the predictions of modern shell-model calculations. Xe and Ba nuclei with A ≈ 135 form an important link in the smooth evolution from spherical to deformed shapes and were investigated after multinucleon-transfer employing the γ-ray tracking array AGATA coupled to the mass spectrometer PRISMA and in complementary fusion-evaporation reactions employing the HORUS γ-ray array at the University of Cologne. Pronounced proton and neutron alignments in the yrast bands of ¹³¹Xe and ¹³⁴Ba were identified. The discoveries of J^π=19/2⁺ and J^π=23/2⁺ isomers in ¹³³Ba, ¹³³Xe and ¹³⁵Ba are closing gaps in the systematics along the N=77 and N=79 isotones towards the proton subshell-closure at Z=64. Exploiting angular-correlation investigations, the ground-state band in ¹³⁶Ba was found to be interrupted by negative-parity states only a few hundred keV above the J^π= 10⁽⁺⁾ isomer. Results on the first spectroscopy of high-spin states above the J^π=8⁻ isomeric bandhead in the odd-odd isotope ¹³⁰I are presented. Large-scale shell-model calculations employing the GCN50:82, SN100PN, PQM130, and a realistic effective interactions reproduce the experimental findings and provide guidance to the interpretation of the observed high-spin features. Supported by the German BMBF (05P15PKFN9 TP1, 05P18PKFN9 TP1) and ENSAR-TNA03.