Dating exposed surface contexts
When one of these particles strikes an atom it can dislodge one or more protons and/or neutrons from that atom, producing a different element or a different isotope of the original element.
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.
'I heard her screaming and I wasn't sure what she was going through,' Rosie Granados told CNN in a heartbreaking interview on Sunday.
Her twin sister, Mary, 29, was one of at least seven people who was killed during the shooting spree.
As oxygen-16 is also common in the atmosphere, the contribution to the beryllium-10 concentration from material deposited rather than created in situ must be taken into account. Each of these nuclides is produced at a different rate.
Both can be used individually to date how long the material has been exposed at the surface.
She was shot and killed when the gunman, Seth Ator, 36, stole her truck as she was delivering mail and talking to her twin sister, Rosie, on the phone.
The cumulative flux of cosmic rays at a particular location can be affected by several factors, including elevation, geomagnetic latitude, the varying intensity of the Earth's magnetic field, solar winds, and atmospheric shielding due to air pressure variations.These nuclides are particularly useful to geologists because they are produced when cosmic rays strike oxygen-16 and silicon-28, respectively.The parent isotopes are the most abundant of these elements, and are common in crustal material, whereas the radioactive daughter nuclei are not commonly produced by other processes.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.Decay rates are given by the decay constants of the nuclides.