Cosmogenic isotopes measurement techniques

Variations in isotopic abundances that are caused by nuclear reactions induced by cosmic rays are most commonly utilized in cosmic ray exposure dating, but this employs isotopes that are measured by either accelerator or noble gas mass spectrometry [28, 29]. In fact, there are only a very limited number of elements that are suitable for the study of cosmogenic isotopic variations, which can be readily analyzed by either TIMS or MC-ICP-MS [28]. The most important application of these techniques are studies of the secondary neutron fluxes that are generated by (primary) cosmic rays. Such measurements aim to detect anomalies in Sm, Gd, and Cd isotopic abundances that are produced by (n,y) reactions, for example " Cd(n, y) Cd. Many of these investigations were conducted by TIMS [137-139], but some cosmogenic Cd isotope variations of lunar rocks and soUs were evaluated based on MC-ICP-MS isotope ratio data that were originally acquired as part of a stable isotope study [134]. 

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