Electron-capture delayed fission probabilities of Es-248 and Es-246 - art.no. 037603

Electron-capture delayed fission was observed in 26-min Es-248 and 7.7-min Es-246, which were produced at the Lawrence Berkeley National Laboratory 88 -Inch Cyclotron via Cf-249(p,2n) and Cf-249(p,4n) reactions at proton energ ies of 18 and 37 MeV on target, respectively. The delayed fission probabili ties were determined to be (3.5+/-1.8) x 10(-6) for Es-248 and (3.7(-3.0)(8.5)) x 10(-5) for Es-246. These values were determined in separate experim ents using our automated rotating wheel online collection and measurement s ystem. Collection and measurement times were optimized for the isotope bein g measured. The measured delayed fission probabilities are consistent with the experimentally observed trend of increasing delayed fission probability with increasing Q value for electron capture.