Almahata Sitta meteorite: gamma -activity measurements at Monte dei Cappuccini Laboratory in Torino

Abstract

The asteroid 2008 TC3 was telescopically seen prior to entering Earth’s atmosphere and was predicted to fall in Sudan on October 7, 2008, as it actually happened. Subsequently, many fragments were collected from the Nubian desert. At Monte dei Cappuccini Laboratory (IFSI, INAF) in Torino, using a selective gamma spectrometer we measured gamma rays from fragment #15, one of the largest retrieved, a ureilite of mass 75 g. Six cosmogenic radionuclides have been measured (/sup46/Sc, /sup57/Co, /sup54/Mn, /sup22/Na, /sup60/Co and /sup26/Al). /sup60/Co and /sup26/Al) . 60Co and 26Al activities allowed us to deduce that the fragment was located at a depth of 41±14 cm inside the 1.5–2m radius asteroid. Moreover, /sup22/Na activity is slightly greater than expected on the basis of the average cosmic ray flux and this could be ascribed to the prolonged solar minimum preceding the meteorite fall.