Alpha decay of 186Pb and 184Hg: The influence of mixing of 0(+) states on alpha -decay transition probabilities.

Abstract

Fine structure in the \ensuremath{\alpha} decay of mass-separated $^{186}\mathrm{Pb}$ and $^{184}\mathrm{Hg}$ has been studied at the GSI on-line mass separator. Alpha singles spectra as well as \ensuremath{\alpha}-x-t and \ensuremath{\alpha}-e-t coincidence events were collected. The \ensuremath{\alpha} decay of $^{186}\mathrm{Pb}$ revealed feeding to a low-lying ${0}^{+}$ state at 328(12) keV in $^{182}\mathrm{Hg}$. This state can be interpreted as being the bandhead of the deformed rotational band observed previously in in-beam studies. In the \ensuremath{\alpha} decay of $^{184}\mathrm{Hg}$, feeding towards the first excited ${2}^{+}$ state at 153 keV and the ${0}_{2}^{+}$ state at 478 keV in $^{180}\mathrm{Pt}$ was observed. The hindrance factor of the \ensuremath{\alpha} decay towards the excited ${0}^{+}$ state gives information about the particle-hole character of the states connected in the \ensuremath{\alpha} decay. A two-level mixing calculation is introduced. From the mixing in Pt and the \ensuremath{\alpha}-decay hindrance factors, small mixing is deduced fro ground stattes of neutron-deficient Hg and Pb nuclei.