A semiclassical theory of crystal-assisted pair production: Beyond the uniform field approximation

By applying the standard trajectory method [M.Kh. Khokonov, H. Nitta, Phys. Rev. Lett. 89 (2002) 094801], a simple expression is obtained for electron-positron pair production by photons in a strong nonuniform electromagnetic field. The expression depends on two parameters: the invariant field parameter χ and the “non-dipole” parameter ν. χ represents the strength of the field while ν depends on the scattering angle of a produced positron/electron. Our numerical calculations agree well with experimental results. It is predicted that the pair production rate reaches its maximum at ∼10 TeV.