By now you already know that Flashes don’t just pop for a fraction of a second. This fraction has a value and its value determines how well it will stop motion (say a splash of liquid). This time is called T.5 (and T.1) and they are explained here.
So every flash manufacturer shares their T.5, and as with many devices there is some variance. Matt Kane of vela.io recently built a device for testing the actual flash duration using an Arduino board and a cheapo diode. The reason for this was to test how the output from strobes (and the vela LED airgap) behave.
Interestingly LED strobes behave differently than Xenon strobes and their fall off patterns is different. They are also much faster (see title image).