Electron-capture delayed fission properties of Es-242 - art. no. 044609

Electron-capture delayed fission of Es-242 produced via the U-233(N-14,5n)E s-242 reaction at 87 MeV (on target) was observed to decay with a half-life of 11+/-3 s, consistent with the reported alpha-decay half-life of Es-242 of 16(-4)(+6) s. The mass-yield distribution of the fission fragments is hi ghly asymmetric. The average pre-neutron emission total kinetic energy of t he fragments was measured to be 183+/-18 MeV. Based on the ratio of the mea sured number of fission events to the measured number of cu decays from the electron-capture daughter Cf-242 (100% alpha branch), the probability of d elayed fission was determined to be 0.006+/-0.002. This value for the delay ed fission probability fits the experimental trend of increasing delayed fi ssion probability with increasing Q value for electron capture.