Photonuclear Experiments: From Bremsstrahlung to Backward Compton Scattering Photons

The features of methods for obtaining information on photonuclear reaction cross sections using beams of bremsstrahlung and quasimonoenergetic photons formed during the in-flight annihilation of relativistic positrons are discussed. These methods have provided the vast majority of data in the nuclear excitation energy up to similar to 40 MeV. It is shown that significant disagreements between the results of such experiments, both in absolute value and shape, are due to certain shortcomings of both methods. These shortcomings can be to a certain extent eliminated by using beams of photons formed in the processes of backward Compton scattering.