High-spin states up to a probable spin I=45/2 have been investigated in ${}_{}{}^{219}{}_{}{}^{}\mathrm{Ac}$ using the reaction ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}$ ${(}^{13}$C,3n). The alternating parity sequences already observed up to I=31/2 do not seem to develop further at higher spins. A new side band was observed as well as several E2/M1 transitions linking the states of positive parity. Multipolarities and mixing ratios were deduced from an analysis of DCO ratios. In addition mixing ratios were obtained independently from the branching ratios. This allows for determination of B(M1)/B(E2) ratios up to ${\mathit{I}}^{\mathrm{\pi }}$=29/$2^{+}$. The data are discussed in terms of a transition from the weak coupling scheme at low and medium spins to the particle-hole regime for I≳31/2.

• Received 16 September 1993

DOI:https://doi.org/10.1103/PhysRevC.49.663