A RADIOATIVIDADE DO METEORITO MARÍLIA (QUEDA DO DIA 5 DE OUTUBRO DE 1971) MEDIDA POR ESPECTROMETRIA GAMA

The activities of the radionuclides Mn 54 , Na 22 , Co 60 , Al 26 and K 40 were measured by low background scintillation gamma-ray spectrometry on two specimen (106 g and 780 g) of the Marília stone meteorite of the fall of October 5, 1971 (Marília, State of São Paulo, Brazil). These activities are, except for potassium 40, due to nuclear reactions induced by the cosmic-ray irradiation of the meteorite in space. From the interpretation of the activities measured, the following results were obtained: potassium content : O.O84% ± 0.005%; mass of the meteorite in space ≥ 50kg; age of cosmic-ray exposure ≥ 1.3 x 10 6 years.