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HK: Fachverband Physik der Hadronen und Kerne

HK 21: Structure and Dynamics of Nuclei IV

HK 21.5: Talk

Tuesday, March 21, 2023, 18:15–18:30, SCH/A215

Structural investigation of neutron-deficient ¹⁶⁸W — •Christoph Fransen¹, Lisa Kornwebel¹, Kalle Auranen², Marcel Beckers¹, Mike Carpenter³, Tuomas Grahn², Paul Greenlees², Rauno Julin², Jan Jolie¹, Filip G. Kondev³, Casper-David Lakenbrink¹, Claus Müller-Gatermann^1,3, Darek Seweryniak³, Franziskus von Spee¹, Nigel Warr¹, and Shaofei Zhu³ — ¹IKP, Univ. of Cologne, Germany — ²JYFL, Jyväskylä, Finland — ³Argonne Natl. Lab, Illinois, USA

In several neutron deficient nuclei in the A=180 region both shape coexistence and rapid shape transitions were identified. Further, B(E2;4₁⁺ → 2₁⁺)/B(E2;2₁⁺ → 0₁⁺) = B_4/2 ratios <1 were found in some neutron deficient Os–W–Pt nuclei far from closed shells. This cannot be explained with any collective model. Shape coexistence could be an explanation, but there are no such cases known so far. Older data [1] yield that ¹⁶⁸W is just at the transition point from “normal” collectivity to the “island” of nuclei with B_4/2<1. However, these data might suffer from assumptions on side feeding of the related states. Therefore, and to learn on the structural evolution within the yrast band of ¹⁶⁸W, we performed an experiment with the recoil distance Doppler-shift technique on ¹⁶⁸W at Argonne National Laboratory with the GAMMASPHERE spectrometer to determine transition strengths from level lifetimes using γγ coincidences. We present these data with respect to rapid shell evolution in this region.

Supported by the DFG, grant Nos. FR 3276/2-1 and DE 1516/5-1.

[1] G.D. Dracoulis et al. Phys. Rev. C 29, 1576 (1984)