Köln 2025 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 7: Structure and Dynamics of Nuclei III

HK 7.1: Vortrag

Montag, 10. März 2025, 16:45–17:00, HS 2 Physik

Investigation of ¹⁶⁸W via lifetime measurement — •Felix Dunkel¹, Christoph Fransen¹, Kalle Auranen², Michael P. Carpenter³, Tuomas Grahn², Paul Greenlees², Jan Jolie¹, Filip G. Kondev³, Casper-David Lakenbrink¹, Claus Müller-Gatermann³, Dariusz Seweryniak³, Franziskus von Spee¹, and Nigel Warr¹ — ¹IKP, Univ. of Cologne, Germany — ²JYFL, Jyväskylä, Finland — ³Argonne Natl. Lab, Illinois, USA

In a cluster of neutron-deficient Os-W-Pt nuclei around A=170, an unexpectedly low ratio of B(E2) transition strengths within the yrast band, with ratios B_4/2 < 1, has been observed. This cannot be explained in standard collective models. Only very recently, B_4/2 < 1 in this region was reproduced with a strong band mixing within an extension of the consistent-Q IBM Hamiltonian [1]. Older lifetime data might suffer from assumptions on side feeding and for the 6₁⁺ only a limit is given. We performed an experiment on ¹⁶⁸W with the RDDS technique at Argonne Natl. Lab. with the GAMMASPHERE spectrometer to determine transition strengths from level lifetimes using γγ coincidences. The measurement of yrast state lifetimes in ¹⁶⁸W will be presented. The new data yield that ¹⁶⁸W is just at the transition point from "normal" collectivity to the island of nuclei with B_4/2 < 1. Furthermore, a ratio of B_6/4 < 1 indicates that the phenomenon is not solely related to the structure of the 2₁⁺ and 4₁⁺ states.

Supported by the DFG, grant Nos. FR 3276/3-1.

[1] F. Pan et al., Phys. Rev. C 110, 054324 (2024)

Keywords: Plunger; lifetime measurement; exotic nuclei; nuclear structure