Cross sections for neutron capture from surrogate measurements: An examination of Weisskopf-Ewing and ratio approximations

Motivated by the renewed interest in the surrogate nuclear reactions approach, an indirect method for determining compound-nuclear reaction cross sections, the prospects for determining (n,{gamma}) cross sections for deformed rare-earth and actinide nuclei are investigated. A nuclear reaction model is employed to simulate physical quantities that are typically measured in surrogate experiments and used to assess the validity of the Weisskopf-Ewing and ratio approximations, which are typically employed in the analysis of surrogate reactions. The expected accuracy of (n,{gamma}) cross sections extracted from typical surrogate measurements is discussed and limitations of the approximate methods are illustrated. Suggestions for moving beyond presently employed approximations are made.