Investigation of the depth-dependent production of long-lived, cosmogeneous radionuclides in meteorites

For the analysis of the long-lived cosmogeneous radionuclides 10Be (T1/2=1.6x106 a), 26Al (T1/2=0.72x106 a), 36Cl (T1/2=0.3x106 a), 41Ca (T1/2=0.1x106 a), 53Mn (T1/2=3.8x106 a), as well as 59Ni (T1/2=0.74x105 a) with the help of the accelerator mass spectrometry, chemical separation processes were developed, which allow an isolation of the elements concerned from a single test specimen of only a few milligrammes of weight. The efficiency of the method was shown with two test facilities: a) the nuclides 10Be, 26Al and 36Cl were tested at the Swiss Technical University in Zurich, b) the nuclide 41Ca was tested at the University in Rehovot (Israel). Besides the radiochemical neutron activation analysis, the radioisotope 53Mn could be detected for the first time by quantitative mass spectrometry at the accelerator plant of the Technical University of Munich. The aliquots of far more than 100 test specimens of meteorites of different classes were analysed for the determination of the contents of 10Be, 26Al, 53Mn and partially 36Cl and 41Ca. For the study of the depth-dependent production of 10Be, 26Al and 53Mn, a series of well documented meteorite test specimens with different preatmospheric radii of the parent meteorites were available. The results are compared with those of model calculations. (orig./RB)