Abstract
The rapid neutron nucleosynthesis process involves an enormous amount of very exotic neutron-rich nuclei, which represent a theoretical and experimental challenge. Two of the main decay properties that affect the final abundance distribution the most are half-lives and neutron branching ratios. Using fragmentation of a primary 238U beam at GSI we were able to measure such properties for several neutron-rich nuclei from 208Hg to 218Pb. This contribution provides a short update on the status of the data analysis of this experiment, together with a compilation of the latest results published in this mass region, both experimental and theoretical. The impact of the uncertainties connected with the beta-decay rates and with beta-delayed neutron emission is illustrated on the basis of r-process network calculations. In order to obtain a reasonable reproduction of the third r-process peak, it is expected that both half-lives and neutron branching ratios are substantially smaller, than those based on FRDM+QRPA, commonly used in r-process model calculations. Further measurements around N ∼ 126 are required for a reliable modelling of the underlying nuclear structure, and for performing more realistic r-process abundance calculations.
Highlights
The third r-process peak at A ⇠ 195, the platinum peak, seems sensitive to both the nuclear physics input and the conditions of the stellar environment as can be seen in the detailed sensitivity study reported in Ref. [1]
Summary and outlook In summary, both theory and experiment, indicate that half-lives in the N ⇠ 126 region near the r-process path should be much smaller than those commonly used in r-process model calculations (FRDM+quasiparticle random-phase approximation (QRPA) model [18])
From the nuclear physics input, such a discrepancy could be removed if neutron emission probabilities were smaller
Summary
The third r-process peak at A ⇠ 195, the platinum peak, seems sensitive to both the nuclear physics input and the conditions of the stellar environment as can be seen in the detailed sensitivity study reported in Ref. [1]. All of the nuclei that lead directly to the formation of the third r-process abundance peak still remain in the region of the. . To a large extent this terra incognita is due to the very low production cross sections, the limited primary beam intensities available at present RIB facilities and the challenging experimental conditions of large backgrounds and very low production rates. This contribution focuses on the impact of half-lives and betadelayed neutrons on the formation of the third r-process peak, and how present theoretical models compare with the experimental data available.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
