Radiative rates for E1, E2, M1, and M2 transitions in Ne-like Cu XX, Zn XXI and Ga XXII

Energy levels, radiative rates and lifetimes are reported for the lowest 139 levels of three Ne-like ions, namely Cu~XX, Zn~XXI and Ga~XXII. These levels mostly belong to the 2s$^2$2p$^6$, 2s$^2$2p$^5$3$\ell$, 2s2p$^6$3$\ell$, 2s$^2$2p$^5$4$\ell$, 2s2p$^6$4$\ell$, and 2s$^2$2p$^5$5$\ell$ configurations. For the calculations the general-purpose relativistic atomic structure package (GRASP) has been adopted. Comparisons are made with earlier available theoretical and experimental results, particularly among the lowest 27 levels of the 2s$^2$2p$^6$ and 2s$^2$2p$^5$3$\ell$ configurations. Due to paucity of similar data for higher lying levels, analogous calculations have also been performed with the flexible atomic code (FAC). These calculations help in assessing the accuracy of our calculated results, especially for the energy levels.