The BALLOON-borne and PAMELA experiments for the study of the antimatter component in cosmic rays

The PAMELA experiment is based on a satellite-borne equipment actually in the final integration phase. It will be installed on board of the Russian satellite Resurs DK1 and launched in a quasi-polar orbit from the Baikonur cosmodrom at the beginning of next year. PAMELA will measure the antiproton and positron fluxes in cosmic rays with high statistics and in a large energy range (80 MeV-190 GeV for antiprotons and 50 MeV-270 GeV for positrons), extending to never investigated energies the measurements of several balloon borne experiments performed by the same PAMELA collaboration in last decade. This will make achievable sensitive tests of cosmic ray propagation models in the Galaxy and the search, in an energy range never investigated before, of possible structures in the fluxes. These structures, related to the presence of primary antiparticle sources, could be signals of "new physics", connected with open problems like dark matter existence and matter/antimatter symmetry in the Universe. The detector consists of a very precise magnetic spectrometer, several scintillation counter hodoscopes to measure the energy losses and times of flight, and a high granularity and deep Si-W calorimeter, augmented by a very compact transition radiation detector and a He3 neutron detector hodoscope, and protected around and on the top by an anticoincidence system. (C) 2003 Elsevier B.V. All rights reserved.