Speaker: Peter Moller and Bill Wilson (T-16)

Calculation of beta-decay properties of nuclei throughout the periodic system; applications to astrophysics and reactor physics

Reliable data bases of beta-decay half-lives and beta-delayed neutron-emission probabilities for large regions of nuclei far from stability are required as input in, for example, modeling of the r-process, modeling of critical assemblies and reactor modeling. We present our model of beta-decay in which transition rates from an initial parent state to ground and excited states in daugther nuclei are obtained as matrix elements of appropriate operators between calculated parent and daughter wave-functions. We present calculated data bases of half-lives and delayed-neutron emission probabilities for nuclei throughout the periodic system. As one application we use the calculated data bases as input in studies of r-process abundances and of its duration. These data, along with improved fission-product yields, are also used in an update of the data library of the CINDER'90 code used in transmutation studies for a wide range of simulations. Examples are given for common fission systems showing greatly improved agreement in temporal delayed neutron emission when compared with measurements.