Coincidence counter

The coincidence counter uses two Geiger counters to measure cosmic rays by ensuring events are recorded only when both counters simultaneously register a particle. Bothe used this technique to show that the laws of conservation of energy and of momentum were as valid for atoms as for billiard balls.
 Walther Bothe Germany 1929 Coincidence counter

The coincidence counter uses two Geiger counters to measure cosmic rays by ensuring events are recorded only when both counters simultaneously register a particle. Bothe used this technique to show that the laws of conservation of energy and of momentum were as valid for atoms as for billiard balls.