RIBF Nuclear Physics Seminar
# β-delayed one and two neutron emission probabilities and the nuclide abundances around the second r-process peak

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Asia/Tokyo

Description

=Date and Place=

Mar. 28th (Tue) 2023 , 13:30~ via Hybrid (Zoom + RIBF hall)

=Lecturer=

Dr. Phong Ho Vi

(Nishina Center, RIKEN)

=Title=

β-delayed one and two neutron emission probabilities and the nuclide abundances around the second r-process peak

=Abstract=

The nucleusynthesis of elements heavier than iron via the rapid (r-) neutron capture process occurs as a sequence of neutron captures and β-decays in very neutron-rich region of nuclear chart. Among the nuclear properties of neutron-rich nuclei that are important in dertemining final r-process abundances, the β-delayed neutron emission probabilities play important roles that smoothen the odd-even staggering pattern and change the amount of neutrons during the freeze-out of neutron captures [1].

In this seminar, the latest and upcoming results from the “Beta-Delayed Neutrons at RIKEN” (BRIKEN) project, which aims at surveying the β-delayed neutron emission probabilities of very neutron-rich nuclei relevant to the r-process nucleosynthesis, will be showcased. As a hightlight of the BRIKEN project, the β-delayed one- and two-neutron emission probabilities (P1n and P2n) of 20 neutron-rich Ag, Cd, In, Sn isotopes were measured [2]. The nuclear shell effects around doubly-magic 132Sn were manifested in the systematic of the measured P1n and P2n values. Our results also provided important benchmarks for the newly developed macroscopic-microscopic and self-consistent global models [3, 4] with inclusion of the statistical treatment of neutron and γ emission. Direct impacts of the measured P1n and P2n on the odd-even staggering of the final r-process abundance around the second r-proces peak were demonstrated, where the observed odd-mass isotopic fractions of Ba in metal-poor stars [5] were found to be better reproduced by using our data.

[1] A. Arcones and G. Martínez-Pinedo. Phys. Rev. C 83, 045809 (2011).

[2] V. H. Phong et al., Phys. Rev. Lett. 129, 172701 (2022).

[3] P. Möller, M. R. Mumpower, T. Kawano, and W. D. Myers, At. Data Nucl. Data Tables 125, 1 (2019).

[4] F. Minato, T. Marketin, and N. Paar, Phys. Rev. C 104, 044321 (2021)

[5] C. Wenyuan et al., Astrophys. J. 854, 131 (2018).