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We have identified two isomers in 254No, built on two- and four-quasiparticle excitations, with quantum numbers K pi = 8- and (14+), as well as a low-energy 2-quasiparticle Kpi = 3+ state. The occurrence of isomers establishes that K is a good quantum number and therefore that the nucleus has an axial prolate shape. The 2-quasiparticle states probe the energies of the proton levels that govern the stability of superheavy nuclei, test 2-quasiparticle energies from theory, and thereby check their predictions of magic gaps.

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Measurements of de-excitation gamma-rays in coincidence with target-like residues produced in deep inelastic transfer reactions of 238 U on a 48 Ca target at an energy near the Coulomb barrier are presented. A systematic analysis of the measured low lying states in the odd and even neutronrich Ca isotopes shows the absence of a predicted shell closure at N = 34 in neutron-rich calcium isotopes.

Fusion-evaporation cross sections for 64 Ni+ 64 Ni have been measured down to the 10 nb level. For fusion between two open-shell nuclei, this is the first observation of a maximum in the S-factor, which signals a strong sub-barrier hindrance. A comparison with the 58 Ni+ 58 Ni, 58 Ni+ 60 Ni, and 58 Ni+ 64 Ni systems indicates a strong dependence of the energy where the hindrance occurs on the stiffness of the interacting nuclei.

The half-life of the 6 + state in 174 Yb of 830(50) µs was incorrectly shown as the mean-life on the level scheme (Fig. 2) and in Table III where transition strengths were listed. Use of the corresponding mean-life of 1198(72) µs and more accurate values for the intensity of the 1265 keV and 628 keV branches leads to the modified transition strengths and hindrances given below, where the main part of the table is reproduced. (Errors are also shown on the reduced hindrances for the 628 and 1265 keV transitions.) The modifications do not affect the original conclusions. Several other typographical errors are corrected in the table, including the unit for magnetic transitions which had been omitted and a degree of forbiddenness of ν = 3 rather than ν = 4 for the 193 keV E2 transition from the 7 − isomer. Also, on p. 8 of the text, in reference to the tunneling estimate for the 6 + , E2 hindrance, the predicted value was given as F = 7.5 × 10 8 . This should have read F = 7.5 × 10 7 which corresponds to the reduced hindrance value f ν = 93 quoted in the text and used in the interpretation.

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The structure and decay properties of high-K isomers in 176 Hf have been studied using beam sweeping techniques and the Gammasphere multi-detector array. A new ∆K = 8 decay branch, from a K π = 22 − , six-quasiparticle, isomeric (t 1/2 = 43µs) state at 4864 keV to the 20 − state of a K π = 14 − band, has been identified. The reduced hindrance factor per degree of K forbiddenness for this decay is measured to be unusually low (f ν = 3.2), which suggests K mixing in the states 2