The nuclide ${}_{}{}^{199}{}_{}{}^{}\mathrm{Rn}$ has been produced in the ${}_{}{}^{169}{}_{}{}^{}\mathrm{Tm}$(${}_{}{}^{35}{}_{}{}^{}\mathrm{Cl}$,$5n$) ${}_{}{}^{199}{}_{}{}^{}\mathrm{Rn}$ reaction. The recoiling ${}_{}{}^{199}{}_{}{}^{}\mathrm{Rn}$ nuclei were separated from the beam at zero degrees by a recoil-separator arrangement utilizing electric and magnetic fields, and detected by their alpha decay signatures in a surface-barrier detector. Two alpha lines were found with energies 6.990±0.015 MeV and 7.060±0.015 MeV. Alpha decay of the known daughter ${}_{}{}^{195}{}_{}{}^{}\mathrm{Po}$ was also observed.

RADIOACTIVITY ${}_{}{}^{199}{}_{}{}^{}\mathrm{Rn}$ and ${}_{}{}^{199}{}_{}{}^{}\mathrm{Rn}_{}^m{}_{}{}^{}$; measured excitation functions ${}_{}{}^{169}{}_{}{}^{}\mathrm{Tm}$(${}_{}{}^{35}{}_{}{}^{}\mathrm{Cl}$,$5n$) ${}_{}{}^{199}{}_{}{}^{}\mathrm{Rn}$ and $E_{\alpha }$'s.

• Received 28 December 1979

DOI:https://doi.org/10.1103/PhysRevC.21.2101