The rate of decay (given the symbol λ) is the fraction of the 'parent' atoms that decay in unit time.
For geological purposes, this is taken as one year.
He is presently employed in the Space & Atmospheric Sciences Group at the Los Alamos National Laboratory.
Radiometric dating--the process of determining the age of rocks from the decay of their radioactive elements--has been in widespread use for over half a century.
The unstable or more commonly known radioactive isotopes break down by radioactive decay into other isotopes.
In 1905, shortly after the discovery of radioactivity, the American chemist Bertram Boltwood suggested that lead is one of the disintegration products of uranium, in which case the older a uranium-bearing mineral the greater should be its proportional part of lead.