Abstract: | The isotopes Fm247, Fm247m and Fm246 were synthesized in the extracted beam of the 310-cm heavy-ion cyclotron in the Joint Institute for Nuclear Research by irradiating Pu239 with C12 ions. ]he procedure of collecting the recoil atoms by means of gas jets is used, with subsequent recording of their ~- decay with Si(Au) detectors. For the isotope Fm247, -activities are obtained with two different half-lives - one with two obviously complex groups of -particles E=7.87±0.05MeV (70%) and EE=7.93±0.05 MeV (30%), whose half- life is T1/2=35±4 sec; the other, with E=8.18±0.03 MeV has T1/2=9.2±2.3 sec. Data are confirmed concerning the properties of the isotope Fm246(E=8.25±0.03MeV and T1/2=1.6±0.4 sec), synthesized in 1966 at The Joint Institute for Nuclear Research.Translated from Atomnaya Énergiya, Vol. 22, No. 5, pp. 342–346, May, 1967. |