Photon Splitting in a Nuclear Electrostatic Field

The cross section for the splitting of a photon into two photons in a nuclear electrostatic field has been calculated from the vacuum polarization. Hamiltonian of Euler and others to first order in $\frac{e^2}{\hslash c}$ for low-energy incident photons ($p<\mathrm{mc}$). For a favorable experimental case, photons of energy 840 kev incident on lead with antiparallel product photons each emitted at 90° relative to the incident photon, the cross section is 2.3×${10}^{-33\mathrm{}}$ ${\mathrm{cm}}^2$/${\mathrm{sterad}}^2$.