HIGH-SPIN STUDIES OF AC-219

High-spin states up to a probable spin I = 45/2 have been investigated in Ac-219 using the reaction Bi-209 (C-13, 3n). The alternating-parit y sequences already observed up to I = 31/2 do not seem to develop fur ther at higher spins. A new sideband was observed as well as several E 2/Ml transitions linking the states of positive parity. Multipolaritie s and mixing ratios were deduced from an analysis of DCO ratios. In ad dition mixing ratios were obtained independently from the branching ra tios. This allowed for determination of B(M1)/B(E2) ratios up to I(pi) = 29/2+. The data are discussed in terms of a transition from the wea k coupling scheme at low and medium spins to the particle-hole regime for I greater than or similar to 31/2.