Threshold Photoneutron Cross Section for ${\mathrm{Mg}}^{26}$ and a Source of Stellar Neutrons

The differential photoneutron cross section for ${\mathrm{Mg}}^{26}$ at 135° has been measured as a function of photon energy from 10 keV to 1.5 MeV above threshold by the threshold photoneutron technique. Several prominent resonances have observed, including one located at 54.3 keV above threshold. The existence of this resonance in the ${\mathrm{Mg}}^{26}$ compound system might provide, through the reaction ${\mathrm{Ne}}^{22}(\alpha , n){\mathrm{Mg}}^{25}$, the primary production mechanism for neutrons in stars.