Cosmogenic neon in mineral separates from Kapoeta: No evidence for an irradiation of its parent body regolith by an early active Sun

We present Ne data from plagioclase separates' from the solar noble-gas-ric h meteorite Kapoeta, obtained mainly by in vacuo etching. Samples rich in s olar gases contain an excess of cosmogenic Ne compared to solar-gas-poor sa mples, testifying to an exposure to cosmic rays in the parent body regolith . The Ne-21/Ne-22 ratio of the excess component is slightly lower than that of the Ne acquired during the meteoroid flight. Model calculations indicat e that the observed isotopic composition of the excess Ne can be produced b y galactic cosmic rays at a reasonable mean shielding of around a hundred t o a few hundred grams per square centimeter. No substantial contribution fr om Ne produced by solar cosmic rays is needed to explain the data. We there fore conclude that they do not offer evidence for a substantially enhanced flux of solar energetic particles early in solar history, contrary to other claims. This conclusion is in agreement with solar flare track data.