In the scintillator photons with big energy and charged particles make flashes which (according to Einstein's photoelectric equation) push electrons out of the photocathode. This get to the first positive charged dynode, from what the elctron pushes more electrons out. This happens at the next dynode and so on. At the end we can see the sign on the anode. In case of slight dynodes (8) we get a fast sign, otherwise with more dynodes (24) we have a punctional sign. With this appliance we cannot detect the way of the particles just the amount of ionisation.