Argon‐37, Argon‐39, and Tritium Radioactivities in the Haverö Meteorite

Abstract

The 37Ar and 39Ar radioactivities were measured in a dissolved and in a melted sample of Haverö. The 37Ar in the metal was 12.4 ± 2.6 dpm/kg (Fe + Ni). The 39Ar in the metal was 49.3 ± 5.5 dpm/kg (Fe + Ni). The 37Ar activity is within 30 percent of that in the Lost City meteorite, while the 39Ar activity is a factor of two higher than in Lost City. The similarity in the 37Ar activities of the metal of the two meteorites indicates that these two bodies had similar preatmospheric sizes. The higher 39Ar activity in the metal of Haverö indicates that the aphelion of Haverö's orbit was at least 4.3 A.U. The 3H radioactivity in Haverö was measured to be 415 ± 30 dpm/kg. The 3H activity combined with the 3He content gives a 3He/23H exposure age for Haverö of (29.5 ± 2.5) X 610 years.

The Haver� meteorite

“…In the meteorite Hayer6 soon after its fall the concentrations of radioactive isotopes have been determined: all, 22Na, 26AI, 37Ar ' 39Ar ' 468c ' 54Mn ' 6OCo (Cressy, 1972;Fireman and Spannagel, 1972;Smith and Fireman, 1973) The results are listed in Table XIV. In the meteorite Hayer6 soon after its fall the concentrations of radioactive isotopes have been determined: all, 22Na, 26AI, 37Ar ' 39Ar ' 468c ' 54Mn ' 6OCo (Cressy, 1972;Fireman and Spannagel, 1972;Smith and Fireman, 1973) The results are listed in Table XIV.…”

“…The 3H activity in the nonmagnetic fraction was 415__+ 30 dpm/kg. However the measured value of 26A1 radioactivity is 77 + 14~ of the 26A1 activity calculated for the meteorite with account of its chemical composition: 54.8 + 9 dpm/kg (Cressy, ]972), 59.4 dpm/kg (Wilkening et al, 1973), 52__+6 dpm/kg (Fireman and Spannagel, 1972). Smith and Fireman (1973) in the nominally magnetic fraction of the meteorite, weighing 3.48 g, have determined the 3H, 3TAr and 39Ar activities.…”