${\mathrm{P}}^{31}(n, p){\mathrm{Si}}^{31}$ and ${\mathrm{Al}}^{27}(n, \alpha ){\mathrm{Na}}^{24}$ Cross Sections

The excitation functions and absolute cross sections for the ${\mathrm{P}}^{31}(n, p){\mathrm{Si}}^{31}$ and ${\mathrm{Al}}^{27}(n, \alpha ){\mathrm{Na}}^{24}$ reactions have been measured by the activation method for neutron energies below 9.5 Mev and at 14.1 Mev. The excitation function for ${\mathrm{P}}^{31}(n, p){\mathrm{Si}}^{31}$ rises from 1.6 Mev to 5.5 Mev, is fairly constant at 0.14 barn to 9.5 Mev and considerably lower at 14 Mev. The ${\mathrm{Al}}^{27}(n, \alpha ){\mathrm{Na}}^{24}$ excitation curve rises from 6 to 9 Mev neutron energy and is greater at 14 Mev. Comparisons are made with earlier measurements of the ${\mathrm{P}}^{31}(n, p){\mathrm{Si}}^{31}$ cross section and some discrepancies appear.