Yield of Alpha Particles from Photonuclear Reactions at 23-Mev Bremsstrahlung

The yield of alpha particles from ($\gamma , \alpha$) reactions and other photoreactions involving alpha-particle emission from 9 elements up to atomic number 58 is given. Much of the data used have been previously published but further information has been obtained on the reactions in carbon, oxygen, and bromine. Original measurements have been made for the ($\gamma , \alpha$) reactions in vanadium and silver. The yield is a maximum in the region of copper and drops rapidly with increasing atomic number. There is evidence that at high atomic numbers, reactions involving the emission of another particle as well as the alpha particle predominate over just single alpha-particle emission.