The Influence of Isomeric States on Independent Fission Product Yields

A simple one-parameter model is presented for calculating the distribution of independent yield strength between ground and isomeric states of primary fission products formed by neutron-induced fission of actinide nuclei. Yield branching ratios are calculated as a function of neutron energy (thermal, fast, and 14-MeV) for 33 cases that span 144 fission product nuclei having isomeric states with known spins.