The exact analytic form for the cross section of pair production must be calculated through quantum electrodynamics in the form of Feynman diagrams and results in a complicated function. To simplify, the cross section can be written as: where is the fine-structure constant, is the classical electron radius, is the atomic number of the material, and is some complex-valued function that depends on the energy and atomic number. Cross sections are tabulated for different materials and energies.
The exact analytic form for the cross section of pair production must be calculated through quantum electrodynamics in the form of Feynman diagrams and results in a complicated function. To simplify, the cross section can be written as: where is the fine-structure constant, is the classical electron radius, is the atomic number of the material, and is some complex-valued function that depends on the energy and atomic number. Cross sections are tabulated for different materials and energies.