Systematics of theKX-Ray Multiplicity for Transitional Nuclei withA≃200

Measurements of the multiplicity of $K$ x rays accompanying (Li,$\mathrm{xn}$) reactions to residual nuclei with $Z\sim 80$ exhibit plateaus of high and constant multiplicity for neutron numbers between 110 and 120, with rapid falloff for both smaller and larger $N$. A proposed explanation for this systematic behavior assumes that strongly coupled, high-$K$ rotational bands are a much more general feature of this transitional mass region than existing data indicate.