Thermal neutron capture in silicon

The prompt gamma-rays from thermal nuteron capture in ${}_{}{}^{28,29,30}{}_{}{}^{}\mathrm{Si}$ have been studied and the radiative capture cross sections determined as 207±4, 120±3 and 107±2 mb, respectively. There has been a marked increase in the number of transitions observed in ${}_{}{}^{29}{}_{}{}^{}\mathrm{Si}$ and a complete decay scheme for this nucleus is presented. Two primary E2 transitions in ${}_{}{}^{29}{}_{}{}^{}\mathrm{Si}$ have been observed and their partial cross sections are compared with the prediction of the direct capture formalism. The measured neutron separation energies are ${\mathit{S}}_{\mathit{n}}$ ${(}^{29}$Si)=8473.61±0.04 keV, ${\mathit{S}}_{\mathit{n}}$ ${(}^{30}$Si)=10 609.21±0.04 keV, and ${\mathit{S}}_{\mathit{n}}$ ${(}^{31}$Si)=6587.32±0.20 keV.