Decay properties of the neutron-deficient isotope Es242

The radioactive decay properties of ²⁴²Es were studied at the gas-filled recoil separator TASCA. This isotope was produced in the $3n$ evaporation channel of the fusion reaction of ⁴⁸Ca+¹⁹⁷Au. A half-life of 16.9(8) s was deduced from 662 α decays of ²⁴²Es, resulting in an α-decay branching of 41(3)%. Twenty-six fission events with a half-life of 18.2_-3.0+4.50.28em0exs were assigned to originate from the electron-capture delayed fission of ²⁴²Es. The probability for the electron-capture delayed fission was measured to be 0.015(4), which improves and resolves ambiguities in available experimental data. We discuss all known cases for electron-capture delayed fission in Es, Bk, and Am isotopes and compare experimental data with predictions from a recent semiempirical model. A cross section of 27(3) nb was measured for the production of ²⁴²Es.