Radionuclides from Space

The determination of long-lived radionuclides by means of accelerator mass spectrometry (AMS) is usually outstandingly successful when an interdisciplinary team comes together. The “heart” of AMS research is of course an accelerator equipped with sophisticated ion sources, analytical tools and detectors run by experienced and ambitious physicists. Setting-up and further developing AMS systems is one of the most interesting and challenging topics.
Another essential part in AMS research is the radiochemical sample preparation preceding the measurement where the goals are: 1.) Enrichment of nuclides of interest by reduction of the matrix. 2.) Depletion of isobars. 3.) Production of a thermally stable chemical compound such as AgCl, AgI, Al₂O₃, BeO, CaF₂, Fe₂O₃, MnO₂ etc. of relatively high purity.
One of the most interesting applications of AMS is the analysis of extraterrestrial material such as meteorites. While being at the surface of their so-called parent body (asteroids, Moon, Mars,…) and again while travelling through space as a so-called meteoroid, these unique pieces are bombarded by high-energy particles from the cosmic radiation. Long-lived radionuclides are produced in the material by nuclear reactions in both stages potentially until saturation. However, they start decaying in a third stage, when meteorites have landed on Earth because the cosmic radiation is shielded by the Earth’s atmosphere and magnetic field. Hence, the concentrations of radionuclides are records of all three stages allowing the reconstruction of the exposure history (duration, shielding, size,…) of the individual meteorite and the cosmic radiation itself.
Meteorite projects and projects with artificially-irradiated targets are also well-suited to develop measurements of “new” AMS radionuclides as the isotopic ratios are at much higher levels (up to 10^-10 radioactive/stable) than e.g. in terrestrial natural samples (10^-14-10^-16). The AMS community is very open to any input and questions from “outside”. The DREsden AMS (DREAMS) and other European AMS facilities offer researchers from academia free measurements via a Trans-National-Access proposal program (www.ionbeamcenters.eu) and also national access (www.dresden-ams.de; DREAMS only).