Production rates of cosmogenic helium‐3, neon‐21, and neon‐22 in ordinary chondrites and the lunar surface |
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| Authors: | J MASARIK K NISHIIZUMI R C REEDY |
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| Abstract: | Abstract— The production of 3He, 21Ne, and 22Ne in meteoroids of various sizes and in the lunar surface was investigated. The LAHET code system, a purely physical model for calculating cosmic‐ray particle fluxes, was used to simulate cosmic‐ray particle interactions with extraterrestrial matter. We discuss the depth and size dependence of the shielding parameter 22Ne/21Ne, which is used for reconstruction of pre‐atmospheric sizes, depth, and exposure histories. The 22Ne/21Ne ratio decreases with increasing depth or pre‐atmospheric size but then increases with depth in very large objects. This increase with depth in the 22Ne/21Ne ratio means that this ratio is a poor indicator of shielding in some large objects. The dependence of 3He/21Ne as function of 22Ne/21Ne was also calculated, and differences between the calculations and the Bern line are discussed. |
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