Direct mass measurements of neutron-rich zinc and gallium isotopes: an investigation of the formation of the first r-process peak

Andrew Jacobs; Stylianos Nikas; John Ash; Behnam Ashrafkhani; Ivana Belosovic; Julian Bergmann; Callum Brown; Jaime Cardona; Eleanor Dunling; Timo Dickel; Luca Egoriti; Gabriella Gelinas; Zach Hockenbery; Sakshi Kakkar; Brian Kootte; Ali Molaebrahimi; Eleni Marina Lykiardopoulou; Tobias Murboeck; Stefan Paul; Wolfgang R. Plass; William S. Porter; Rane Simpson; Coulter Walls; Yilin Wang; Jens Dilling; Ania Kwiatkowski

arXiv · 2309.11716

Direct mass measurements of neutron-rich zinc and gallium isotopes: an investigation of the formation of the first r-process peak

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Abstract

The prediction of isotopic abundances resulting from the rapid neutron capture process (r-process) requires high-precision mass measurements. Using TITAN's on-line time-of-flight spectrometer, first time mass measurements are performed for $^{83}$Zn and $^{86}$Ga. These measurements reduced uncertainties, and are used to calculate isotopic abundances near the first r-process abundance peak using astrophysical conditions present during a binary neutron star (BNS) merger. Good agreement in abundance across a range of trajectories is found when comparing to several metal-poor stars while also strongly deviating from the solar r-process pattern. These findings point to a high degree of sensitivity to the electron fraction of a BNS merger on the final elemental abundance pattern for certain elements near the first r-process peak while others display universality. We find that small changes in electron fraction can produce distinct abundance patterns that match those of metal-poor stars with different classifications.

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Andrew Jacobs, Stylianos Nikas, John Ash, Behnam Ashrafkhani, Ivana Belosovic, Julian Bergmann, Callum Brown, Jaime Cardona, Eleanor Dunling, Timo Dickel, Luca Egoriti, Gabriella Gelinas, Zach Hockenbery, Sakshi Kakkar, Brian Kootte, Ali Molaebrahimi, Eleni Marina Lykiardopoulou, Tobias Murboeck, Stefan Paul, Wolfgang R. Plass, William S. Porter, Rane Simpson, Coulter Walls, Yilin Wang, Jens Dilling, Ania Kwiatkowski. 2025-01-16. Direct mass measurements of neutron-rich zinc and gallium isotopes: an investigation of the formation of the first r-process peak. https://arxiv.org/abs/2309.11716

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