Half-life systematics across the N=126 shell closure: role of first-forbidden transitions in the β decay of heavy neutron-rich nuclei

A I Morales; J Benlliure; T Kurtukián-Nieto; K-H Schmidt; S Verma; P H Regan; Z Podolyák; M Górska; S Pietri; R Kumar; E Casarejos; N Al-Dahan; A Algora; N Alkhomashi; H Álvarez-Pol; G Benzoni; A Blazhev; P Boutachkov; A M Bruce; L S Cáceres; I J Cullen; A M Denis Bacelar; P Doornenbal; M E Estévez-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 Mücher; B Rubio; H Shaffner; S J Steer; A Tamii; S Tashenov; J J Valiente-Dobón; P M Walker; H J Wollersheim; P J Woods

doi:10.1103/PhysRevLett.113.022702

Half-life systematics across the N=126 shell closure: role of first-forbidden transitions in the β decay of heavy neutron-rich nuclei

Phys Rev Lett. 2014 Jul 11;113(2):022702. doi: 10.1103/PhysRevLett.113.022702. Epub 2014 Jul 11.

Authors

A I Morales¹, J Benlliure¹, T Kurtukián-Nieto¹, K-H Schmidt², S Verma¹, P H Regan³, Z Podolyák⁴, M Górska², S Pietri⁴, R Kumar⁵, E Casarejos¹, N Al-Dahan⁴, A Algora⁶, N Alkhomashi⁴, H Álvarez-Pol¹, G Benzoni⁷, A Blazhev⁸, P Boutachkov², A M Bruce⁹, L S Cáceres², I J Cullen⁴, A M Denis Bacelar⁹, P Doornenbal², M E Estévez-Aguado¹, G Farrelly⁴, Y Fujita¹⁰, A B Garnsworthy⁴, W Gelletly⁴, J Gerl², J Grebosz¹¹, R Hoischen¹², I Kojouharov², N Kurz², S Lalkovski⁹, Z Liu¹³, C Mihai¹⁴, F Molina¹⁵, D Mücher⁸, B Rubio¹⁵, H Shaffner², S J Steer⁴, A Tamii¹⁶, S Tashenov², J J Valiente-Dobón¹⁷, P M Walker⁴, H J Wollersheim², P J Woods¹³

Affiliations

¹ Universidade de Santiago de Compostela, E-15782 Santiago de Compostela, Spain.
² GSI, Planckstrasse 1, D-64291 Darmstadt, Germany.
³ Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom and National Physical Laboratory, Teddington, Middlesex TW11 0LW, United Kingdom.
⁴ Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom.
⁵ GSI, Planckstrasse 1, D-64291 Darmstadt, Germany and IFAC, New Delhi, India.
⁶ IFIC, CSIC-Universidad de Valencia, E-46071 Valencia, Spain and Institute of Nuclear Research of the Hungarian Academy of Sciences, Debrecen H-4001, Hungary.
⁷ INFN, Università degli Studi di Milano, I-20133 Milano, Italy.
⁸ IKP, University of Cologne, D-50937 Cologne, Germany.
⁹ School of Computing, Engineering and Mathematics, University of Brighton, Brighton BN2 4GJ, United Kingdom.
¹⁰ Department of Physics, Osaka University, 560-0043 Osaka, Japan.
¹¹ The Henryk Niewodniczànski Institute of Nuclear Physics, PL-31-342 Kraków, Poland.
¹² Department of Physics, Lund University, S-22100 Lund, Sweden.
¹³ School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom.
¹⁴ Horia Hulubei National Institute of Physics and Nuclear Engineering (IFIN-HH), RO-077125 Bucharest-Magurele, Romania.
¹⁵ IFIC, CSIC-Universidad de Valencia, E-46071 Valencia, Spain.
¹⁶ Research Center for Nuclear Physics (RCNP), Osaka University, 567-0047 Osaka, Japan.
¹⁷ INFN-Laboratori Nazionali di Legnaro, I-35020 Legnaro, Italy.

PMID: 25062171
DOI: 10.1103/PhysRevLett.113.022702

Abstract

This Letter reports on a systematic study of β-decay half-lives of neutron-rich nuclei around doubly magic (208)Pb. The lifetimes of the 126-neutron shell isotone (204)Pt and the neighboring (200-202)Ir, (203)Pt, (204)Au 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 β 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 β decay back to stability.