Cosmic Ray Production of Rare Gas Radioactivities and Tritium in Lunar Material

Abstract

The argon radioactivities ³⁷Ar and ³⁹Ar were obtained by vacuum melting from interior and exterior portions of rock 10057 and from a portion of the fines from the bulk sample container. The release of argon and tritium as a function of the temperature was followed for the fine material. A comparison is made of the activities observed in the lunar samples with those expected from the spallation of iron, titanium, and calcium. From these data and the ³⁸Ar content, the cosmic ray exposure age of rock 10057 is deduced as 110 x 10⁶ years.