Studying Photonuclear Reactions with Emission of α Particles on Natural Osmium and Iridium

For the first time, we have measured the flux-weighted average yields of (γ, α) reactions on targets of natural osmium and iridium for a bremsstrahlung beam with a cutoff energy of 55.5 MeV. Theoretical calculations including an α-particle preproduction factor of ~10–2 provide a satisfactory description of experimental data. It has been established that at photon energies below 55 MeV, nonstatistical mechanisms of charged particle emission predominate.