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This question has several parts.

  1. How does modern science catch free neutrons that are just floating around?
  2. Is there anyway to "pull" a neutron off any atom that does not involve our current nuclear reactors?

They're not very controlled with tons of other forms of radiation so, I was wondering if there is a clean, and more controlled way to get our hands on neutrons alone.

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1 Answer

Neutron sources

You can buy a commercial off-the shelf "neutron generator", or you can use a radioactive source.

Neutron generators are accelerator-based fusion reactors1 and have the advantage of being able to simply turn the neutron supply on and off.

The most common source is AmBe (Americium-241/Beryllium), though Californium-252 and tritium both have their uses. I also built a Po-210/C-13 source once as part of my work on KamLAND. Sources require no external power supply and no maintenance (though they do decay away if you use a short half-life progenitor like Po-210), but they run continually.

Free neutrons

You basically can't "catch" free neutrons in the sense of collecting a bunch of them in one place.

On the other hand, thermal neutrons (those whose kinetic energy in on scale of that of room temperature gasses) can "capture" on a variety of atoms. Hydrogen-1 and Carbon-12 are the most common nuclei that can capture a free neutron. Chlorine, boron and especially Gadolinium are useful because they have high thermal neutron capture cross-sections.

1 Yes, fusion reactors. They've been around for many decades. The fusion "problem" is in getting ones that generate more power than you put in.

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Besides having a hard time 'grabbing' free neutrons, they will all have decayed into protons after a while; elusive little bastards... –  Wojciech Morawiec Jan 1 at 23:59
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