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A K isomer with a half-life of (110±10) ms at an excitation energy of 1254keV has been identified in the nucleus 252No . The isomer is interpreted as a two-quasineutron state with K π = 8- . The isotope 252No was produced in the fusion-evaporation reaction 206Pb(48Ca, 2n)252No . The experiment has been performed at the velocity filter SHIP of GSI Darmstadt. [ABSTRACT FROM AUTHOR]

The decay of the isotopes 255Rf, 251No and 247Fm produced in the reactions $\mathrm{{}^{207}Pb\ensuremath({}^{50}Ti,2n){}^{255}Rf\ {}^{\alpha}_{\rightarrow}\ {}^{251}No\ \ensuremath{}^{\alpha}_{\rightarrow}\ {}^{247}Fm}$ , and $\mathrm{{}^{206}Pb\ensuremath({}^{48}Ca,3n){}^{251}No\ \ensuremath{}^{\alpha}_{\rightarrow}\ {}^{247}Fm}$ was investigated by means of α-γ spectroscopy. Previously observed γ transitions in coincidence with α decays of 255Rf were confirmed, their energies and line intensities were measured more precisely, and their multipolarities were determined as E1. In 251No a new isomeric state at E * > 1700keV with a half-life of ≈ 2μs was identified. The decay of 247Fm was measured more precisely. A partial level scheme of the daughter nucleus 243Cf could be established. [ABSTRACT FROM AUTHOR]