[sethhovestol]

It is the case that particles always try to settle into the lowest energy, and the more options they have the faster. We may be able to engineer places where they're stable, like in the example from my grandparent of a neutron. They are unstable since their mass is greater than the mass of a proton and an electron combined, but they're stable in all common elements we're used to. So much so that we think of radioactive elements as the exception, but (mostly) all that's happening there (in beta decay) is a neutron decaying. I'm not an expert, but I'd imagine making a stable situation for a heavier particle much harder than just making an atom, and the fine grained control is even hard still.