NEW NUCLIDES PU-228, PU-229

In continuation of our work on investigation of the neutron-deficient plutonium isotopes [1] we carried out the experiments aimed to produce new isotopes Pu-228, Pu-229. The isotope Pu-228 has been produced in the bombardment of the Pb-228 target with a beam of Mg-24 and the isot ope Pu-229 -- in the reactions of Pb-207, Pb-208 targets with Mg-26 pr ojectiles. The isotopes were identified after in-flight separation fro m the beam and target-like particles by the VASSILISSA electrostatic s eparator [2] and implantation into silicon strip detectors. The assign ment of unknown alpha-decays was made by establishing their genetic po sition and time correlations with those belonging to known alpha-decay chains. The alpha-decay energies of Pu-228, Pu-229 were measured to b e (7810 +/- 20) keV and (7460 +/- 30) keV, respectively.