Photoprotons from Magnesium

Abstract

The distributions in energy and in angle of the protons ejected from magnesium by the bremsstrahlung x-rays of a 24-Mev betatron have been observed in nuclear emulsions. Both normal magnesium and enriched ${\mathrm{Mg}}^{25}$ show a uniform angular distribution for all proton energies. The energy distribution of the protons from enriched ${\mathrm{Mg}}^{25}$ is compared to the distributions calculated from an evaporation process using various energy level densities. Good agreement is obtained using the known ${\mathrm{Na}}^{24}$ level densities. The integrated cross section of the ${\mathrm{Mg}}^{25}(\gamma ,p)$ reaction is determined as 0.056±0.03 Mev-barn.