Cosmogenic nuclide burial dating
Decay rates are given by the decay constants of the nuclides.
These equations can be combined to give the total concentration of cosmogenic radionuclides in a sample as a function of age.
Both can be used individually to date how long the material has been exposed at the surface.
Because there are two radionuclides decaying, the ratio of concentrations of these two nuclides can be used without any other knowledge to determine an age at which the sample was buried past the production depth (typically 2–10 meters).
Cosmogenic nuclides such as these are produced by chains of spallation reactions.
The production rate for a particular nuclide is a function of geomagnetic latitude, the amount of sky that can be seen from the point that is sampled, elevation, sample depth, and density of the material in which the sample is embedded.
This isotope may be produced by cosmic ray spallation of calcium or potassium.
e V) particles composed mostly (90 %) of atomic nuclei but with some photons (gamma rays), electrons, and positrons.
The majority (90 %) of the atomic nuclei are protons (H nuclei), the rest are alpha particles (He nuclei, 9 %) and nuclei heavier atoms (1 %).
In rock and other materials of similar density, most of the cosmic ray flux is absorbed within the first meter of exposed material in reactions that produce new isotopes called cosmogenic nuclides.
At Earth's surface most of these nuclides are produced by neutron spallation.