They are detected by nuclear interactions that produce secondary charged particles. Often one uses a moderator, such as paraffin, to slow the neutrons and thus increase the detection efficiency. These detectors are used to monitor the neutron fluxes in the vicinity of a reactor or accelerator. Liquid scintillators can measure both neutrons and gamma rays. By carefully measuring the shape of the electronic signal, scientists can and distinguish between these two types of particles.
Neutrinos interact very weakly with matter and are therefore very hard to detect.
Thus, neutrino detectors must be very large. This is a Cerenkov counter in which the interaction of the neutrino with the heavy water produces an electron moving faster than the speed of light in the water. The moving electron generates a cone of light that can be observed with photomultiplier tubes. Information from these tubes will be used to determine the energy and direction of the incident neutrino. As the energy increases, large and even more complex detection systems are needed, some involving thousands of individual detectors.