Absolute Cross Sections for the ReactionsB11(γ, 2p)Li9andC12(γ, 3p)Li9

Activation curves for the reactions ${\mathrm{B}}^{11}(\gamma , 2p){\mathrm{Li}}^9$ and ${\mathrm{C}}^{12}(\gamma , 3p){\mathrm{Li}}^9$ were obtained in the energy range 100-320 Mev. Targets of boron and carbon were exposed to the bremsstrahlung beam of the synchrotron and the yields of ${\mathrm{Li}}^9$ measured by counting the delayed neturons in a moderator-counter assembly surrounding the targets. The activation curves were analyzed by the photon difference method to obtain the cross-section curves as a function of energy. Both cross sections show a pronounced increase above 150 Mev, and have integrated values up to 320 Mev of 2.0±0.3 Mev-millibarns for the reaction ${\mathrm{B}}^{11}(\gamma , 2p){\mathrm{Li}}^9$ and 0.31±0.05 Mev-millibarn for the reaction ${\mathrm{C}}^{12}(\gamma , 3p){\mathrm{Li}}^9$.