Time of flight detector

A time of flight (TOF) detector is a particle detector which can discriminate between a lighter and a heavier elementary particle of same momentum using their time of flight between two scintillators. The first of the scintillators activates a clock upon being hit while the other stops the clock upon being hit. If the two masses are denoted by m 1 and m 2 and have velocities v 1 and v 2 then the time of flight difference is given by

where L is the distance between the scintillators. The approximation is in the relativistic limit at momentum p and c denotes the speed of light in vacuum. Usually, δ t is the apparatus' time resolution (~200 ps).