Migdal's and Khokhlov's Calculations of the Nuclear Photoeffect

We compare Migdal's calculation of ${\sigma }_{-2\mathrm{}}=\int \sigma W^{-2\mathrm{}}\mathrm{dW}$ with experimental data on the nuclear photoeffect. The experimental data for seven nuclei from Al to U agree with the equation ${\sigma }_{-2\mathrm{}}=3.5\mathrm{}{A}^{\frac{5}{3}}$ μb/Mev; while Migdal's calculation gives an equation of this form, but with a smaller coefficient. We show that Migdal's calculation gives a mean energy ${\left(\frac{{\sigma }_{\mathrm{int}}}{{\sigma }_{-2\mathrm{}}}\right)}^{\frac{1}{2}}$ in essential agreement with Jensen's two-fluid model calculation of the resonance energy. We then compare Khokhlov's and Levinger's calculations of the bremsstrahlung-weighted cross section ${\sigma }_b$ for a finite square well with each other, and with experimental data, and find agreement with the equation ${\sigma }_b=0.30\mathrm{}{A}^{\frac{4}{3}}$ mb. In the appendix we give a very simple calculation of the polarizability $\alpha$ of the deuteron, with the result $\alpha =0.64\mathrm{}\times {10}^{-39\mathrm{}}$ ${\mathrm{cm}}^3$.