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

{\displaystyle m_{1}}

and

m

2

{\displaystyle m_{2}}

and have velocities

v

1

{\displaystyle v_{1}}

and

v

2

{\displaystyle v_{2}}

then the time of flight difference is given by

Δ

t

=

L

(

1

v

1

−

1

v

2

)

≈

L

c

2

p

2

(

m

1

2

−

m

2

2

)

{\displaystyle \Delta t=L\left({\frac {1}{v_{1}}}-{\frac {1}{v_{2}}}\right)\approx {\frac {Lc}{2p^{2}}}(m_{1}^{2}-m_{2}^{2})}

where

L

{\displaystyle L}

is the distance between the scintillators. The approximation is in the relativistic limit at momentum

p

{\displaystyle p}

and

c

{\displaystyle c}

denotes the speed of light in vacuum.