(aka Associated particle imaging)
irradiate ore with fast neutrons with an energy of 14.1 MeV, which arise in a binary nuclear reaction
d+3Н -> 4He+n.
In this reaction, the neutron and α-particle (4He nucleus) scatter almost in opposite directions.
Therefore, by registering the α-particle accompanying the neutron, it is possible to determine the direction of neutron emission (neutron tagging).