Cherenkov light reverse cone direction

Question

The Cherenkov cone is emitted along the charged particle direction as many textbooks say.

Detectors like Super-Kamiokande can detect those cerenkov rings and tag the particle as a muon-like neutrino event or electron-like neutrino event.

My problem is that there are also other pictures in the internet for cherenkov radiation emitted in reverse direction which i cannot understand. It would mean, the cherenkov-light is travelling faster than the charged particle.

Maybe someone can make it clear for me.

Source:

http://www-sk.icrr.u-tokyo.ac.jp/sk/detector/cherenkov-e.html

http://large.stanford.edu/courses/2014/ph241/alaeian2/

Answer 1

Both images actually show different steps in the emission:

• The first image tries to motivate how the Cherenkov light, that is emitted along the path of the charged particle, superimposes to a light front emitted at a certain angle

• The yellow cones in the second image visualise how this light front then propagates further

Maybe it helps if you mentally combine both images into something like this:

(sorry for the quick and dirty sketch)