Neutron capture cross section of unstable 63Ni: implications for stellar nucleosynthesis

TL;DR

This study measures the neutron capture cross section of unstable 63Ni for the first time, providing data crucial for understanding nucleosynthesis in massive stars and supernovae.

Contribution

The paper presents the first experimental measurement of the 63Ni(n,γ) cross section and its impact on stellar nucleosynthesis models.

Findings

New resonance capture kernels determined

Maxwellian Averaged Cross Sections calculated with 20% uncertainty

Significant influence on s-process element production in massive stars

Abstract

The $^{63}$Ni($n, \gamma$) cross section has been measured for the first time at the neutron time-of-flight facility n\_TOF at CERN from thermal neutron energies up to 200 keV. In total, capture kernels of 12 (new) resonances were determined. Maxwellian Averaged Cross Sections were calculated for thermal energies from kT = 5 keV to 100 keV with uncertainties around 20%. Stellar model calculations for a 25 M$_\odot$ star show that the new data have a significant effect on the $s$-process production of $^{63}$Cu, $^{64}$Ni, and $^{64}$Zn in massive stars, allowing stronger constraints on the Cu yields from explosive nucleosynthesis in the subsequent supernova.