The anti-neutrino coming from the nuclear reactor interacts with a proton of the
target, giving a positron and a neutron. The positron annihilates with an electron
of target and gives two simultaneous photons. The neutron slows down before being
eventually captured by a cadmium nucleus, that gives the emission of photons about
one 15 microseconds after those of the positron. All those photons are detected
and the 15 microseconds identify the "neutrino" interaction.
Didier Verkindt