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Production rates of cosmogenic helium‐3, neon‐21, and neon‐22 in ordinary chondrites and the lunar surface
Author(s) -
MASARIK J.,
NISHIIZUMI K.,
REEDY R. C.
Publication year - 2001
Publication title -
meteoritics and planetary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 100
eISSN - 1945-5100
pISSN - 1086-9379
DOI - 10.1111/j.1945-5100.2001.tb01906.x
Subject(s) - neon , chondrite , meteoroid , cosmic ray , helium , physics , astrobiology , atomic physics , astrophysics , meteorite , argon
— The production of 3 He, 21 Ne, and 22 Ne 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 22 Ne/ 21 Ne, which is used for reconstruction of pre‐atmospheric sizes, depth, and exposure histories. The 22 Ne/ 21 Ne ratio decreases with increasing depth or pre‐atmospheric size but then increases with depth in very large objects. This increase with depth in the 22 Ne/ 21 Ne ratio means that this ratio is a poor indicator of shielding in some large objects. The dependence of 3 He/ 21 Ne as function of 22 Ne/ 21 Ne was also calculated, and differences between the calculations and the Bern line are discussed.