Creation of relativistic positronium. II. Photoproduction cross sections including Coulomb corrections

Previous Born approximation calculations of the photoproduction of singlet (para) positronium are extended to give the cross section to all orders in the atomic number Z, i.e., to include Coulomb correction. At the same time the cross section for triplet (ortho) positronium production-which does not exist in Born approximation-is obtained to all orders in Z. The calculations and results are given in a form closely related to the well-known high-energy pair production cross section including Coulomb corrections. The relations to pair production are discussed. [S1050-2947(99)06309-X].