Modify one of the examples (B1, B4, etc. ), making the geometry to be a set of trackers. (7 layers, using silicon, 10*20*0.1 cm*cm*mm, layer-to-layer distance: 30 cm, material of world volume: vacuum)
Beam on electron, gamma, proton with 100 MeV, check the event display.
Part 2:
Beam on using proton, 100 MeV, and use hit information on the tracker (get hit position and time), to calculate momentum for each event.