The production of cosmogenic nuclides in stony meteoroids by galactic cosmic-ray particles

We present a purely physical model for the calculation of depth- and size-d ependent production rates of cosmogenic nuclides by galactic cosmic-ray (GC R) particles. Besides the spectra of primary and secondary particles and th e excitation functions of the underlying nuclear reactions, the model is ba sed on only one free parameter-the integral number of GCR particles in the meteoroid orbits. We derived this value from analysis of radionuclide data in Knyahinya. We also shaw that the mean CCR proton spectrum in the meteoro id orbits has been constant over about the last 10 Ma. For the major target elements in stony meteoroids, we present depth- and size-dependent product ion rates for Be-10, C-14, Al-26, Cl-36, and Mn-53 as well as for the rare gas isotopes He-3, Ne-20, Ne-21, Ne-22, Ar-36, and Ar-38. The new data diff er from semi-empirical estimates by up to a factor of 4 but agree within si milar to 20% with results obtained by earlier parametric or physical approa ches. The depth and size dependence of the shielding parameter Ne-22/Ne-21 and the correlations Al-26 vs. Be-10, Al-26 vs Mn-53, Be-10/Ne-21 vs. Ne-22 /Ne-21, and Ar-36 vs. Cl-36 for deciphering preatmospheric sizes, shielding depths, terrestrial residence times, and exposure histories are also discu ssed.