Photonuclear Cross Sections forA40

The ($\gamma , p$), ($\gamma , \mathrm{np}$), ($\gamma , n$), and ($\gamma , 2n$) cross sections for ${\mathrm{A}}^{40}$ are presented. The ($\gamma , p$) cross section has a peak at 23.5 Mev while the ($\gamma , n$) cross section peaks at 16.5 Mev and the ($\gamma , 2n$) peaks at 20 Mev. The ($\gamma , \mathrm{np}$) cross section peaks at 27.5 Mev. The total absorption cross section for ${\mathrm{A}}^{40}$ has a peak height of 86 mb at 23.5 Mev and a full width at half maximum of 10.3 Mev. The integrated total cross section is 470±70 mb-Mev to 23 Mev and 900±180 mb-Mev to 40 Mev. The shapes of these cross sections are discussed and a need for further investigation of energy and angular distributions of photoprotons from argon is indicated.