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

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