Half-Lives of Argon-37, Argon-39, and Argon-42

The half-lives of three argon isotopes have been carefully determined, with the following results: Ar(37), 35.1 +/- 0.1 days; Ar(39) 269 +/- 3 years; Ar(42), 32.9 +/- 1.1 years. By combining the Ar(42) value with earlier data, a cross section of 0.5 +/- 0.1 barn is calculated for the reaction, with thermal neutrons, Ar(41)(n,gamma)Ar(42).

Cosmogenic Carbon-14 in Meteorites and Terrestrial Ages of "Finds" and Craters

Carbon-14 has been measured in several stone and iron meteorites. For "falls," the C(14)/Al(26) ratios in stones and the C(14)/Cl(36) ratios in irons are consistent with constant irradiation. The stone "finds" have radiocarbon ages of up to >/= 21,000 years. The Henbury craters are apparently </= 7,000 and the Odessa craters >/= 11,000 years old.