Resonance neutron-capture cross sections of stable magnesium isotopes and their astrophysical implications

Abstract

We have measured the neutron capture cross sections of the stable magnesium isotopes ${}^{24,25,26}$Mg in the energy range of interest to the $s$ process using the neutron time-of-flight facility n_TOF at CERN. Capture events from a natural metal sample and from samples enriched in ${}^{25}$Mg and ${}^{26}$Mg were recorded using the total energy method based on C${}_{6}$${}^{2}$H${}_{6}$ detectors. Neutron resonance parameters were extracted by a simultaneous resonance shape analysis of the present capture data and existing transmission data on a natural isotopic sample. Maxwellian-averaged capture cross sections for the three isotopes were calculated up to thermal energies of 100 keV and their impact on $s$-process analyses was investigated. At 30 keV the new values of the stellar cross section for ${}^{24}$Mg, ${}^{25}$Mg, and ${}^{26}$Mg are 3.8$\ifmmode\pm\else\textpm\fi{}$0.2 mb, 4.1$\ifmmode\pm\else\textpm\fi{}$0.6 mb, and 0.14$\ifmmode\pm\else\textpm\fi{}$0.01 mb, respectively.