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Message: <blockquote data-quote="freyar" data-source="post: 6690576" data-attributes="member: 40227">First off, ask away!When you say "an electron is produced in a tube," I guess you're talking about electron guns found in old cathode ray tube televisions, etc.  In those, free electrons are produced by heating a piece of metal to a high enough temperature that the electrons "boil off." Then an electric field is used to pull the electrons away from the metal and accelerate them.Neutrinos, on the other hand, are trickier.  They are produced in nature; for example, the sun makes a lot of them, some radioactive decays produce neutrinos, a supernova produces a tremendous number, etc.  But we also want to make neutrinos for experiments to study them.  Some experiments use nuclear reactors, since various nuclear reactions including radioactive decay of unstable "daughter" nuclei can make neutrinos.  There are also experiments that need a high intensity beam of neutrinos, which takes a multi-step process.  First, you accelerate protons to very high energies, and then you smash them into a fixed target (like a piece of graphite).  This produces a bunch of junk, including some short-lived subatomic particles called pions.  Some pions are charged, so you can separate them from the other particles by sending everything through a magnetic field and selecting only the pions.  Then the pions decay, producing neutrinos and electrons/positrons, which you then just let hit a wall or something.  Meanwhile, the neutrinos just go right through the wall to your detector, which can sometimes be hundreds of miles away through the earth.</blockquote>

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