The neutrons have the following property as they do not carry any charge. It is very difficult to detect neutrons. So, indirect methods are employed to detect neutrons. This consist of an arrangement where alpha or beta particles or gamma-rays are produced by colliding neutrons with a certain nuclear material.
Indirect Method to detect Neutrons
It consists of a setup in which a slow-moving neutron collides with the atom of an isotope of uranium. The uranium atom splits into two or more parts due to fission process. This produces nuclear radiations in the form of alpha, beta and gamma rays. These nuclear radiations are detected by Geiger Muller tube, ionization tube, and scintillation counters. Hence, by measuring the intensity of the radiations, the intensity of neutron beam producing them can be detected.
Note: Only slow-moving neutrons will cause fission. The fast-moving neutrons are first to slow down by spraying a layer of paraffin on the top of the uranium layer of the detector.