The space mission PAMELA

Abstract Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) is a satellite-borne experiment which will investigate the matter–antimatter (a)symmetry of the universe and other cosmological problems through precise cosmic-ray measurements. The primary objectives of the PAMELA mission include measurements of the energy spectra of cosmic-ray antiprotons and positrons over a large energy range (up to 190 GeV for antiprotons, 270 GeV for positrons) and with unprecedented accuracy, the search for an antimatter component with a sensitivity of 10 −7 in the He /He ratio, the measurement of the light nuclear components of cosmic rays up to 200 GeV/n and of the electron component up to at least 400 GeV. The apparatus is built around a permanent magnetic spectrometer equipped with a double-sided silicon microstrip tracking system and surrounded by a scintillator anticoincidence system. State-of-the-art detectors are used for particle identification: a silicon–tungsten imaging calorimeter, augmented by a scintillator shower tail catcher, and a transition radiation detector made up of carbon fibre radiators and proportional straw tubes. Fast scintillators are used for time-of-flight measurements and to provide the primary trigger. A neutron detector is finally provided to extend the range of particle measurements to energies as high as 10 11 –10 13 eV. PAMELA will be operated on-board of the Resurs-DK1 satellite, which will be put into its semi-polar orbit in 2004. Here we illustrate the main features of the apparatus and its current status