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HK: Fachverband Physik der Hadronen und Kerne

HK 49: Nuclear Astrophysics IV

HK 49.1: Gruppenbericht

Mittwoch, 13. März 2024, 17:30–18:00, HBR 14: HS 4

First study of the ¹³⁹Ba(n,γ)¹⁴⁰Ba reaction to constrain the conditions for the astrophysical i process — •Dennis Muecher¹, Artemis Spyrou², Pavel Denissenkov³, Falk Hervig³, Magne Guttormsen⁴, Ann-Ceceilie Larsen⁴, and Mathis Wiedeking⁵ — ¹Institut für Kernphysik, Universität zu Köln — ²FRIB, Michigan State University, USA — ³Department of Physics and Astronomy, University of Victoria, Canada — ⁴Department of Physics, University of Oslo, Norway — ⁵SSC Laboratory, iThemba LABS, South Africa

The intermediate "i" process was proposed as a plausible scenario to explain some of the unusual abundance patterns observed in metal-poor stars (Denissenkov et al, ApJ Letters 2017). The most important nuclear physics properties entering i-process calculations are the neutron-capture cross sections and they are almost exclusively not known experimentally. In this talk we demonstrate results (Spyrou et al., under review at PRL, 2023) from an experiment using RIBs from CARIBU, Argonne National Laboratory, allowing to experimentally constraint the ¹³⁹Ba(n,γ)¹⁴⁰Ba reaction rate using the newly developed "Shape" method (Muecher et al., PRC 107, L011602, 2023). Our results remove the dominant source of uncertainty for the production of lanthanum, a key indicator of i-process conditions. Our results show that the observed elemental abundances in metal-poor stars are consistent with an i-process scenario at neutron densities of 10¹³ n/cm³.

Keywords: nucleosynthesis; i process; neutron capture rates; Oslo method