An Analysis of -delayed neutron emission of even-even neutron-rich nuclei with proton-neutron QRPA

Minato, Futoshi   ; Iwamoto, Osamu  

-decay and -delayed neutron emission of neutron-rich spherical nuclei are investigated. Our formalism adopts a self-consistent QRPA approach for -decay and Hauser-Feshbach statistical model for particle evaporation from highly excited state of daughter (precursor) nucleus. In this work, we particularly pay attention to the effects of two contributions. One is tensor force, which is not taken into account in conventional self-consistent QRPA but is important for reproducing half-lives of closed-shell nuclei. And another is isospin finite range pairing. They play a significant role to reduce energy of excited state of precursor nuclei. We found that these effects reduce the number of decay branches above neutron threshold of precursor nuclei and consequently a predicted -delayed neutron yields become smaller than that without them. This work is planned to apply to nuclear data evaluation of -delayed neutron yield of fission fragments in future.