Half-lives of <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mmultiscripts><mrow><mi mathvariant="normal">Rn</mi></mrow><mprescripts></mprescripts><mrow></mrow><mrow><mn>199</mn></mrow><mrow></mrow><mrow></mrow></mmultiscripts></mrow></math></span> and <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mmultiscripts><mrow><mi mathvariant="normal">Rn</mi></mrow><mrow></mrow><mrow><mi>m</mi></mrow><mrow></mrow><mrow></mrow><mprescripts></mprescripts><mrow></mrow><mrow><mn>199</mn></mrow><mrow></mrow><mrow></mrow></mmultiscripts></mrow></math></span>

H. A. Enge; M. K. Salomaa; A. Sperduto; W. Schier; H. E. Wegner

doi:10.1103/PhysRevC.24.298

Half-lives of ${}^{199}{Rn}$ and ${}^{199}{Rn}^{m}$

H. A. Enge, M. K. Salomaa, A. Sperduto, W. Schier, and H. E. Wegner

Phys. Rev. C 24, 298 – Published 1 July 1981

Abstract

The nuclide ${}^{199}{Rn}$ and the isomer ${}^{199}{Rn}^{m}$ were produced in the reaction ${}^{169}{Tm} ({}^{35}{Cl}, 5 n) {}^{199}{Rn}$ . An electromagnetic velocity filter separated the recoiling residual nuclei from the beam at zero degree. The nuclei were embedded into a surface-barrier detector recording both the arrival pulse and the alpha-decay event. The half-life for ${}^{199}{Rn}$ in its presumed ground state ( $E_{a} = 6.99$ MeV) has been determined as 0.5 ± 0.2 sec and the half-life of ${}^{199}{Rm}^{m}$ ( $E_{a} = 7.06$ MeV) is 0.29 ± 0.05 sec.