Feeding of High-Spin Particle Yrast States by Collective Structures in the Continuum

The population of yrast states in ${}_{}{}^{152}{}_{}{}^{}\mathrm{Dy}$ and properties of continuum $\gamma$ rays have been measured as a function of input angular momentum, $l$, via the ${}_{}{}^{122}{}_{}{}^{}\mathrm{Sn}$(${}_{}{}^{34}{}_{}{}^{}\mathrm{S}$,$4n$) reaction. With increasing $l$ an eventual saturation of the high-spin population with a narrow region of yrast feeding is observed, together with an enhanced yield in the continuum spectra. This implies that the decay of very-high-spin states is diverted from the yrast line by continuum cascades and suggests collective modes which might be built on high-$J$ particle states.