Prompt and Delayed Spectroscopy of Ac isotopes around $N=$126

Nuclei above $Z=$82 and around $N=$126 are well described by the spherical shell model, with the attractive proton-neutron residual interactions and particle-octupole vibration coupling resulting in energy-favored, isomeric states occurring along the yrast line. Nuclei up to Z$=$88 are mostly well known [1], but information on Ac ($Z=$89) isotopes is limited. We report on high-spin, gamma-ray spectroscopy measurements of $^{214,215,216,217}$Ac performed at the Australian National University using the CAESAR array and fusion-evaporation reactions between $^{12}$C and $^{14,15}$N beams delivered by the 14UD accelerator incident on $^{204}$Pb and $^{209}$Bi targets. States up to 29/2$^{+}$ isomers were known previously in $^{215,217}$Ac [2,3], while only one gamma-ray has been assigned to each of $^{214,216}$Ac. New level schemes have now been constructed for $^{214,216}$Ac and those for $^{215,217}$Ac have been significantly extended. The results will be presented in detail together with semi-empirical shell model calculations that support the proposed level schemes. \\[4pt] [1] G. D. Dracoulis et. al., Phys. Rev. C 80, 054320 (2009).\\[0pt] [2] D. J. Decman et. al., Nuclear Physics A 436 (1985) 311-337.\\[0pt] [3] D. J. Decman et. al., Z. Phys. A 310, 55-59 (1983).