Production of antimatter in the galaxy

The astronomical dark matter could be made of weakly interacting massive species whose mutual annihilations should produce antimatter particles and distortions in the corresponding energy spectra. The propagation of cosmic rays inside the Milky Way plays a crucial role and is briefly presented. The uncertainties in its description lead to considerable variations in the predicted primary fluxes. This point is illustrated with antiprotons. Finally, the various forthcoming projects are rapidly reviewed with their potential reach.Comment: Invited talk at the TAUP 2005 Conference in Zaragoza (Spain

First Result from the Alpha Magnetic Spectrometer on the International Space Station: Precision Measurement of the Positron Fraction in Primary Cosmic Rays of 0.5char21350 GeV

A precision measurement by the Alpha Magnetic Spectrometer on the International Space Station of the positron fraction in primary cosmic rays in the energy range from 0.5 to 350 GeV based on 6.8 x 10(6) positron and electron events is presented. The very accurate data show that the positron fraction is steadily increasing from 10 to similar to 250 GeV, but, from 20 to 250 GeV, the slope decreases by an order of magnitude. The positron fraction spectrum shows no fine structure, and the positron to electron ratio shows no observable anisotropy. Together, these features show the existence of new physical phenomena