Shrimp radiometric dating
Some star dust particles embedded in early-formed meteorites contain highly anomalous isotope concentrations when compared with normal abundances for the Earth, sun and normal meteorites.
How these bits of dust escaped homogenization is not clear, but their pristine chemistry makes them an important link to possible interstellar sources for the stuff in the solar nebula.
The ions exit the magnet in a broad beam, then enter an electrostatic compensator, which re-organizes them according to mass only, removing the effects of energy differences between ions of the same mass.
The result, on the exit end of the electrostatic compensator, is a spectrum of ions perfectly organized in order of increasing mass from hydrogen, with an atomic mass of one, up to uranium, with an atomic mass of 238.
A brand new .5 million, 12-ton instrument called the SHRIMP arrived at Stanford this past April and is poised to answer these and other fundamental questions about the origins of our Earth and solar system.
The SHRIMP is well equipped for both these types of isotopic studies, because it has the resolution to measure and compare ions with very small mass differences and the sensitivity to obtain good results from very small samples, typically a limiting factor in extraterrestrial research.
By way of radiometric dating and isotopic fingerprinting.
In both cases, the key is the isotopes atoms of the same element that have slight differences in mass.
Radiometric dating uses certain isotopes of uranium and thorium which over time turn to lead by radioactive decay.
By measuring relative abundances of the original isotopes and their decay products, it is possible to calculate the age in millions of years of a very old rock.
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Rocks and minerals that Stanford scientists are preparing for the SHRIMP include bits of stardust from very old meteorites, minerals from far-traveled sedimentary basins in western Canada, and samples from deep crustal rocks coughed up by volcanoes in the Bering Strait region, near the border between Alaska and Russia.