PAMELA Instrument Print
                                                                                               Astropart. Phys. 27 (2007) 296
 Pamela Telescope

The concept of the PAMELA telescope is based on:

  • A Magnetic Spectrometer, based on a neodymion-iron-boron permanent magnet and a precision tracking system.
    Charged particles passing through the instrument aperture are deflected by the magnetic field. The resulting curved trajectories depend on the electric charge-sign and magnetic rigidity (Momentum/ charge) of the particles. The sign of the electric charge is determined with a very high confidence degree, and the momentum of the particle is measured up to the highest energies for which a useful statistics for flux of rare particles, as antiprotons and positrons, can be collected;
  • A sampling imaging Calorimeter, in which pairs of orthogonal ministrip silicon sensor planes are interleaved with tungsten absorber plates. The energy released by the interacting particle (and indeed of the extra energy in case of an annihilation event) are measured and the interaction topology of the particle inside the calorimeter is reconstructed. The imaging calorimeter is the primary means of distinguishing electrons and positrons from antiproton and proton with the same charge sign and momentum, giving a separation factor on the order of 105. Observing the annihilation pattern of antiprotons and possible antinuclei, a confirmation of their identity on an "event by event" basis is obtained;
  • A precise Time Of Flight system, using plastic scintillation detectors, measures the charge of the incident particles, the versus of their flight, for albedo rejection, and the velocity of low enery particles, to determining, combined with the rigidity, the mass. The coincidence of TOF scintillators provides flight reprogrammable fast trigger to initiating event digitisation and read out.
  • An Anticoincidence system, based on plastic scintillation counters placed at sides and around top of the magnet and at sides of the instrument between the first and the second counter layer of TOF flags events in which particles may have entered through the magnet or have produced in pairs with only one traversing the detector.
  • A Neutron Detector, composed by 3He counters and polyethylene neutron moderators , to distinguishing primary protons and electrons at energies 1011-1013 eV with a rejection factor of about 10-4.
  • A Bottom Scintillator counter for triggering independently the neutron detector.
  • A Pamela service module including On-Board Data Handling (OBDH), power supply and telemetry system.


    Edited by Laura Marcelli