Unlike other radiometric dating techniques, those using the uranium decay series ( except for those using the stable final isotopes 206 Pb and 207 Pb ) compare the ratios of two radioactive unstable isotopes.
12.
Such " decay series ", such as the uranium-radium and thorium series, were known within a few years of the discovery of radioactivity, and provided a basis for constructing techniques of radiometric dating.
13.
The white lead in the painting " The Supper at Emmaus " had polonium-210 values of 8.5?.4 and radium-226 ( part of the uranium-238 radioactive decay series ) values of 0.8?.3.
14.
While the average rate of production of 220 Rn ( from the thorium decay series ) is about the same as 222 Rn, the amount of 220 Rn in the environment is much less than that of 222 Rn because of the short half-life of 220 Rn ( 55 seconds, versus 3.8 days respectively ).
15.
The isotope 210 Po is the penultimate member of the uranium-radium-decay series; it decays into a stable lead-isotope with a half-life of 138 days . In almost all cases, the decay is via the emission of an alpha particle of 5.305 MeV . Only in one case of 100000, an alpha particle of lower energy appears; in this case, the decay leads to an excited level of 206 Pb, which then decays to the ground state via gamma radiation.
