Interpretation of cosmogenic nuclides in meteorites on the basis of accelerator experiments and physical model calculations

Cosmogenic nuclides in extraterrestrial matter provide a wealth of informat ion on the exposure and collision histories of small objects in space and o n the history of the solar and galactic cosmic radiation. The interpretatio n of the observed abundances of cosmogenic nuclides requires detailed and a ccurate knowledge of their production rates. Accelerator experiments provid e a quantitative basis and the ground truth for modeling cosmogenic nuclide production by measurements of the relevant cross sections and by realistic simulations of the interaction of galactic protons with meteoroids under c ompletely controlled conditions, respectively. We review the establishment of physical model calculations of cosmogenic nuclide production in extrater restrial matter on the basis of such accelerator experiments and exemplify this approach by presenting new experimental and theoretical results for th e cosmogenic nuclide Ti-44. The model calculations describe all aspects of cosmogenic nuclide production and allow the determination of long-term sola r and galactic cosmic ray spectra and a consistent interpretation of cosmog enic nuclides in extraterrestrial matter.