New nuclides228,229Pu

In continuation of our work on investigation of the neutron-deficient plutonium isotopes [1] we carried out the experiments aimed to produce new isotopes228,229Pu. The isotope228Pu has been produced in the bombardment of the208Pb target with a beam of24Mg and the isotope229Pu — in the reactions of207,208Pb targets with26Mg projectiles. The isotopes were identified after in-flight separation from the beam and target-like particles by the VASSILISSA electrostatic separator [2] and implantation into silicon strip detectors. The assignment of unknown α-decays was made by establishing their genetic position and time correlations with those belonging to known α-decay chains. The α-decay energies of228,229Pu were measured to be (7810±20) keV and (7460±30) keV, respectively.