Some of them can reach the material of the detectors unaltered, so that they can interact with it.
This sounds like electrons leaving their valence shell, not too much i learnt about LHC detector but i know the little knowledge i got from this article will play out well for me in the future. THANK YOU @lemouth
In this case, electrons are in fact produced not from atoms, but either from the annihilation or the decay of other particles. I hope this clarifies.