Cross Sections for theAl27(γ,π+)Mg27Reaction

Cross sections for the ${\mathrm{Al}}^{27}(\gamma ,{\pi }^{+}){\mathrm{Mg}}^{27}$ reaction have been determined by measuring the ${\mathrm{Mg}}^{27}$ radioactivity that was produced in aluminum samples that were irradiated with bremsstrahlung of maximum energy varying from 100 to 300 MeV. The observed yields were corrected for the contributions from secondary neutron reactions. The resulting cross sections have a maximum value of 13 μb at 220 MeV and the integrated cross section to 300 MeV is 1.38±0.24 MeV mb. These values are a factor of about 10 smaller than those reported previously for this reaction by Masaike et al. The cross sections for the ${\mathrm{Al}}^{27}(\gamma ,{\pi }^{+})$ reaction are compared with those observed previously for similar reactions involving other light target nuclei and are discussed in terms of an extension of the theory outlined by Laing and Moorhouse for reactions of this type.