Orateur
Description
Recent observations of metal-poor star elemental and isotopic abundances [Roe22, Wen18] have sparked new interest in the nucleosynthesis of elements around the second r-process abundance peak, as it may shed light on the r-process conditions. To understand the r-process conditions and link these observations to astrophysical models, it is crucial to have information on the nuclear properties of the radioactive progenitors of the second r-process peak.
Following r-process freezeout, the final abundances of the second peak are the result of various competing reactions, such as neutron capture, photodisintegration, fission, and β-delayed neutron emission. The latter has been the main focus of our experiment, conducted within the BRIKEN project [Tol19] at the RIBF facility of RIKEN (Japan).
In the present contribution, we will present new experimental results on β-delayed one and two neutron emission probabilities of very neutron-rich nuclei located south-east of 132Sn [Pho20] and compare them with recent macroscopic-microscopic and self-consistent global models with the inclusion of the statistical treatment of neutron and γ emission [Kaw08, Min21]. The impact of our results on the odd-even staggering of the final r-process abundance around the second r-process peak, as well as the observed odd-mass isotopic fractions of Ba in metal-poor stars [Wen18] will be presented. Continuing our experimental program on r-process nuclei, we will present a new experimental setup that will allow β-decay and β-delayed neutron spectroscopy studies to be conducted in parallel with MR-TOF mass measurements program at RIKEN RIBF.
References
[Roe22] I. U. Roederer et al., Astrophys. J. Suppl. Ser. 260, 27 (2022).
[Wen18] C. Wenyuan et al., Astrophys. J. 854, 131 (2018).
[Pho20] V. H. Phong, Phys. Rev. Lett. 129, 172701 (2022)
[Tol19] A. Tolosa-Delgado et al., Nucl. Instr. And Methods A, 925, 133 (2019)
[Kaw08] T. Kawano, P. Möller, and W. B. Wilson, Phys. Rev. C 78, 054601 (2008).
[Min21] F. Minato et al., Phys. Rev. C 104, 044321 (2021).
[Ros22] M. Rosenbusch et al., Nucl. Instr. And Methods A, 1047, 167824 (2023)
