The High Energy Particle Detector (HEPD-02) detecs individual incident particles. In particular, for each particle it identifies the type (proton, electron, nucleus), measures the energy and determines the angle between the flight line and the Earth’s magnetic field line to the Equator (pitch angle). HEPD-02 can detect particle flows coming from the Van Allen belts and determine with great accuracy the magnetospheric region of their origin, with the aim of obtaining the energy spectrum and the composition of the particles of the stability bands that suddenly fall into the atmosphere, in case of external disturbances (“Particle burst”).

The instrument, shown in the figure, consists of:

  • a first trigger plane TR1 (overall dimensions 200×180 mm2) segmented in 5 plastic scint. bars (2 mm thick);
  • an incident particle angle detector DD (“tracker”) made of five standalone tracking modules (“turrets”), each composed of three sensitive planes (“staves”);
  • a second trigger plane TR2 (overall dimensions 150 x 150 mm2) segmented in 4 plastic scint. bars (8 mm thick);
  • an energy detector ED composed of:

     – 12 plastic scint. planes (150 x 150 x 10 mm3);

      – 2 crystal (LYSO) scint. planes (overall dimensions 150 x 150 mm2) segmented in 3 bars (50 mm thick);

  • a containment detector CD (not shown here) surrounding the calorimeter on 5 sides, made of plastic scint. planes (4 lateral and 1 bottom plane), 8 mm thick

The energy range explored is 3 – 100 MeV for electrons and 30 – 200 MeV for protons.

The Qualification Model (QM) is completely assembled and it is ready for the space qualification tests.

The Flight Model (FM) is at the final stage of development for the physics tests that are scheduled during the month of December.

HEPD-02