Direct capture in the ${}^{130}$Sn(n,$\gamma$)${}^{131}$Sn and ${}^{132}$Sn(n,$\gamma$)${}^{133}$Sn reactions under $r$-process conditions

Abstract

The cross sections of the ${}^{130}$Sn(n,$\gamma$)${}^{131}$Sn and ${}^{132}$Sn(n,$\gamma$)${}^{133}$Sn reactions are calculated in the direct capture model at low energies below 1.5\,MeV. Using recent data from (d,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 input 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 two. The stellar reaction rates $N_A<\sigma v>$ show a slight increase with temperature. Finally an estimate for the influence of low-lying resonances to the stellar reaction rates is given.

Comments: 5 pages, 3 figures, Phys. Rev. C, Brief Report, accepted for publication