Half-Life Systematics across the N=126 Shell Closure: Role of First-Forbidden Transitions in the beta Decay of Heavy Neutron-Rich Nuclei

A. I. Morales*, J. Benlliure, T. Kurtukian-Nieto, K. -H Schmidt, S. Verma, P. H. Regan, Z. Podolyak, M. Gorska, S. Pietri, R. Kumar, E. Casarejos, N. Al-Dahan, A. Algora, N. Alkhomashi, H. Alvarez-Pol, G. Benzoni, A. Blazhev, P. Boutachkov, A. M. Bruce, L. S. CaceresI. J. Cullen, A. M. Denis Bacelar, P. Doornenbal, M. E. Estevez-Aguado, G. Farrelly, Y. Fujita, A. B. Garnsworthy, W. Gelletly, J. Gerl, J. Grebosz, R. Hoischen, I. Kojouharov, N. Kurz, S. Lalkovski, Z. Liu, C. Mihai, F. Molina, D. Muecher, B. Rubio, H. Shaffner, S. J. Steer, A. Tamii, S. Tashenov, J. J. Valiente-Dobon, P. M. Walker, H. J. Wollersheim, P. J. Woods

*Corresponding author for this work

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This Letter reports on a systematic study of beta-decay half-lives of neutron-rich nuclei around doubly magic Pb-208. The lifetimes of the 126-neutron shell isotone Pt-204 and the neighboring Ir200-202, Pt-203, Au-204 are presented together with other 19 half-lives measured during the "stopped beam" campaign of the rare isotope investigations at GSI collaboration. The results constrain the main nuclear theories used in calculations of r-process nucleosynthesis. Predictions based on a statistical macroscopic description of the first-forbidden beta strength reveal significant deviations for most of the nuclei with N <126. In contrast, theories including a fully microscopic treatment of allowed and first-forbidden transitions reproduce more satisfactorily the trend in the measured half-lives for the nuclei in this region, where the r-process pathway passes through during beta decay back to stability.

Original languageEnglish
Article number022702
Number of pages5
JournalPhysical Review Letters
Issue number2
Publication statusPublished - 11 Jul 2014


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