E1andM2transitions in the neon isoelectronic sequence

Using relativistic and nonrelativistic Hartree-Fock methods we have calculated some $E1\mathrm{}$ and $M2\mathrm{}$ transition probabilities for $2p^{5}3d\to 2p^6+\gamma$ and $2p^{5}3s\to 2p^6+\gamma$ in the Ne isoelectronic sequence. The heaviest ion considered is U. The relativistic effects on both the photon energies and the transition amplitudes are discussed. A comparison of our calculated $M2\mathrm{}$ lifetimes with experimental results for the $2p^{5}3s-2p^6$ transition in Ne-like Cu shows significant differences, while the calculated $E1\mathrm{}$ lifetimes for Ne-like Cl indicates good agreement with experiment.