PRESENT STATUS OF DELBRUCK SCATTERING

Recent developments in the theory of Delbruck scattering and experimental results obtained after the latest review article of 1975 are discussed. Theoretical predictions and experimental data are in a general agreement at energies below 12 MeV, except for the Coulomb correction effect which remains to be calculated. Information on the relative size of the Coulomb correction effect compared to the lowest-order Born approximation is extracted from the experimental data. In the 20 to 100 MeV energy range Delbruck scattering has also been clearly identified, but furthergoing studies are desirable both on the experimental and theoretical sides. In the high-energy range above 1 GeV the high-energy small-angle approximation leads to a satisfactory agreement with experiment. Attention is paid to the interference of Delbruck scattering with atomic Rayleigh scattering and with scattering through the excitation of different modes of nuclear excitation.