Direct capture in the130Sn(n,γ)131Sn and132Sn(n,γ)133Sn reactions underr-process conditions

Abstract

The cross sections of the ${}^{130}$Sn($n,\phantom{\rule{-0.16em}{0ex}}\ensuremath{\gamma}$)${}^{131}$Sn and ${}^{132}$Sn($n,\phantom{\rule{-0.16em}{0ex}}\ensuremath{\gamma}$)${}^{133}$Sn reactions are calculated in the direct capture model at low energies below 1.5 MeV. Using recent data from ($d\phantom{\rule{-0.16em}{0ex}},\phantom{\rule{-0.16em}{0ex}}p$) transfer experiments on ${}^{130}$Sn and ${}^{132}$Sn, it is possible to avoid global input parameters with their inherent uncertainties and to determine all inputs to the direct capture model by local adjustments. The calculated direct capture cross sections of ${}^{130}$Sn and ${}^{132}$Sn are almost identical and have uncertainties of less than a factor of 2. The stellar reaction rates ${N}_{A}\ensuremath{\langle}\ensuremath{\sigma}v\ensuremath{\rangle}$ show a slight increase with temperature. Finally, an estimate for the influence of low-lying resonances to the stellar reaction rates is given.