24-29 June 2018
LNGS
Europe/Rome timezone

The beta-Oslo method: experimentally constrained (n,g reaction rates relevant to the r-process)

28 Jun 2018, 16:15
15m
"E. Fermi" conference room (LNGS)

"E. Fermi" conference room

LNGS

Via G. Acitelli, 22 - 67100 Assergi (Italy)

Speaker

Ann-Cecilie Larsen (University of Oslo)

Description

All elements found in our Universe, except for the very lightest ones, have been created during stars' lives and/or deaths. Burbidge, Burbidge, Fowler and Hoyle pointed out the slow neutron-capture and the rapid neutron-capture process to be the main contributors for producing elements from iron to uranium. On August 17, 2017, the LIGO and Virgo gravitational-wave detectors measured, for the first time, a direct signal from two colliding neutron stars. Follow-up measurements with telescopes sensitive to electromagnetic radiation confirmed that the r-process had indeed taken place in the collision (Ref.~\cite{Pian2017}). Hence, a long-standing question in nuclear astrophysics was solved; at least one astrophysical r-process site is now identified. However, the uncertain nuclear-physics input remains a huge obstacle in modeling the r-process yields in large-scale nucleosynthesis network calculations. The r-process inevitably involves highly neutron-rich nuclei, where there is a severe lack of relevant nuclear data such as masses, beta-decay rates and neutron-capture cross sections. Well away from the valley of stability, different theoretical predictions for neutron-capture rates may vary with several orders of magnitude. In this talk, a recently developed method to address this issue is presented: the beta-Oslo method provides data on the nuclear level density and average gamma-decay strength of moderately neutron-rich nuclei. These quantities are crucial input for calculations of neutron-capture rates, which in turn play a key role in a "cold" r-process scenario. The beta-Oslo method presents a first step towards constraining neutron-capture rates of importance to the r-process. References E.~M.~Burbidge \textit{et al.}, Rev. Mod. Phys. \textbf{29}, 547 (1957). B.~P.~Abbott \textit{et al.}, Phys. Rev. Lett. \textbf{119}, 161101 (2017). E. Pian \textit{et al.}, \textit{Nature} \textbf{551}, 67 (2017). M. Arnould, S. Goriely, and K. Takahashi, Phys. Rep. {\bf 450}, 97 (2007). A.~Spyrou \textit{et al.}, Phys. Rev. Lett. \textbf{113}, 232502 (2014). S.~N.~Liddick \textit{et al.}, Phys. Rev. Lett. \textbf{116}, 242502 (2016).

Primary author

Ann-Cecilie Larsen (University of Oslo)

Co-authors

Artemis Spyrou (NSCL/MSU) Magne Guttormsen (University of Oslo) Sean N. Liddick (Michigan State University)

Presentation Materials