Stima e rilevamento della radioattività cosmogenica in asteroidi e meteoriti: applicazione a Bennu (missione OSIRIS-REx)

In October 2020, NASA's OSIRIS-REx mission collected surface material from the asteroid Bennu, with the aim of returning it to Earth in late 2023. Like every celestial body in the heliosphere, Bennu is constantly hit by a stream of cosmic rays, which, as it interacts with the atoms within the material, produces isotopes of various elements. Some of these nuclei are radioactive and find wide use in numerous areas of research. In particular, radionuclides of different half-lives can be studied to determine the cosmic-ray exposure history of the object to which they belong. In this thesis, the depth-dependent radioactivity trend of different nuclides in Bennu is calculated with two methods: the first, based on so-called physical and semi-empirical models, has already been widely used; the second, a Geant4 simulation, is new in this field. The aim is to estimate the radioactivity of the Bennu sample and the time of measurement required to reveal its radioactivity. The measurement will be performed using gamma-ray spectrometers at the Monte dei Cappuccini Laboratory in Turin, Italy. The new method for the radioactivity calculation is also validated by the application to different meteorites.