Electron-capture delayed fission properties of 244Es -: art. no. 024612

Electron-capture delayed fission was observed in 37-s Es-244 produced via the Np-237(C-12,5n)Es-244 reaction at 81 MeV (on target) with a production cross section of 0.31+/-0.12 mub. The kinetic energies of coincident fission fragments were measured with our rotating wheel detection system and the average pre-neutron-emission total kinetic energy of the fragments was found to be 186+/-19 MeV. The mass-yield distribution of the fission fragments is predominantly asymmetric. Based on the ratio of the number of fission events to the measured number of alpha decays from the electron-capture daughter Cf-244 (100% alpha branch), the probability of delayed fission was determined to be (1.2+/-0.4) X 10(-4). This value for the delayed fission probability fits the experimentally observed trend of increasing delayed fission probability with increasing Q value for electron capture.