How can we detect neutrons? If I am asked to design a simple experiment to detect neutrons, how can I do that?
The problem is, neutron is a neutral particle. So, application of electric and magnetic fields won't help. Can I detect them by photographic plate? And even if I am able to detect, how can I design an experiment with it?
 A: Generally neutron detectors are built around detection of nuclear reactions that occur in the presence of neutron radiation. For a simple example, if helium-3 is exposed to thermal neutrons, it tends to interact like:
$$ \rm ^3He + n\to {^3H}+{^1H} $$
producing a proton and a tritium nucleus, both of which are created with a fair amount of energy and thus tend to be ionized. At this point the detection of the resulting ionized gas is similar to a more conventional particle detector you may already be familiar with.
A: You could purchase a commercial scintillator cell, even good, large, new ones go for under 4000$. There, typically a photomultiplier is coupled to a liquid scintillator, or to a solid state crystal. Read out the signal with an oscilloscope or other digitizer. Find some pulse shape algorithm of your liking and let it run over each recorded pulse. At low energies, you will see two populations, one from electronic recoils, caused by gamma and beta backgrounds, and one from nuclear recoils, caused by neutrons. If you are on a shoestring budget, you can reduce the volume of the scintillator, and use SiPMs instead, but then your rate of neutrons will get so low that you'll have a hard time doing anything with it.
