Produzione di nuclei e antinuclei nei decadimenti del Bottomonio e nel continuo a E_{CM} ~ 10 GeV

The subject of this thesis is the search for anti-deuteron and anti-triton in the annihilation of $\Upsilon(1S)$ and $\Upsilon(2S)$, using the samples collected by the Belle experiment at the KEKB e^+e^- collider. The presence of anti-deuteron in $\Upsilon(1S)$ and $\Upsilon(2S)$ decays was first discovered by the Argus Collaboration and then confirmed by the CLEO Collaboration, but at present time no precise measurement of its spectrum from both the states is available. The study of the spectrum allows to test the so called coalascence model, that predicts the anti-deuteron to be bound only after the recombinations of anti-protons and anti-neutrons in the final state. The anti-triton has never been observed in this environment, but measurements of its production in heavy ion collisions are available: a comparison of the A dependence of (anti)nuclei production in bottomonium decays and heavy ion colllisions can therefore be made. A careful study of the detector response to a highly ionizing particle is needed, as its performance has been optimized for pion and kaon identification: the validation of the simulation tools represents the central part of this study. After the definition of the selection criteria, control samples of deuteron and tritium are successfully isolated and the strategy for the measurement of the yield of anti-deuteron and anti-tritium (and anti-helium-3) is finalized.