Spectroscopy ofRn204,206,208and the systematic behavior ofZ=86isotopes

A spectroscopic investigation of the radon isotopes ${}_{}{}^{204,206,208}{}_{}{}^{}\mathrm{Rn}$ was performed by means of the reactions ${}_{}{}^{192,194,196}{}_{}{}^{}\mathrm{Pt}$(${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$,$4n$)${}_{}{}^{204,206,208}{}_{}{}^{}\mathrm{Rn}$ and ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$(${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$,$5n$)${}_{}{}^{206}{}_{}{}^{}\mathrm{Rn}$ with ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ energies between 85 and 110 MeV and ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ energies between 80 and 94 MeV. $\gamma -\gamma$ coincidences, pulsed beam yield functions, angular distributions, and pulsed beam isomeric decay rates were measured. The yrast and near-yrast level structure was established to $J\sim 15\hslash$, and in each of the three nuclei two isomers above the known $J^{\pi }=8^{+}$ state were observed. The systematic trends for the $Z=86\mathrm{}$ isotopes are compared with the behavior expected in a single particle model, and increased collectivity is found with decreasing neutron number. Analogies are made with the $N=86\mathrm{}$ system.