Radioactive species produced by cosmic rays in Bruderheim and other stone meteorites

In this paper we report measurements of the activity of 16 radioactive nuclides in the chondritic meteorite Bruderheim, which fell on March 4, 1960. The data are compared with those for the iron Aroos and other stone, iron, and stony-iron meteorites. For nuclides of A≥46, the activities normalized to iron and nickel content are closely similar. For lower A, the activities in stone are mainly produced in lighter elements. The spectrum of bombarding particles is shown to be closely similar in irons and stones. The results are consistent with a constant cosmic-ray intensity. Cosmic-ray bombardment ages of 30×106 years for Bruderheim and 130×106 years for Admire are calculated from rare-gas data and the activities of Na22, Al26, and Cl36.