TITLE: Follow-Up on Proton to Neutron Tranformation
QUESTION [2 upvotes]: This is a follow-up to a question I asked a couple of months ago.
I'm familiar with the concept that a proton can be transformed into a neutron if it is supplied with 1.29 MeV of energy. I've done extensive research, but I can't seem to find the answers to some burning questions I had. I hope someone can help answer these:

Does this idea of proton-to-neutron only apply to protons in the nucleus, free protons, or both?
If this is the case, would accelerating a proton fast enough (causing a gain 1.29 MeV of energy) cause it to convert into a neutron? If so, has this been done before? And was it done with free protons or protons in the nucleus?
I'm familiar with the Cowan-Reines experiment and how antineutrinos were used to convert protons to neutrons. Are we limited only to antineutrinos to cause such a transformation? Or could any elementary particle (say, an electron) cause a proton to convert into a neutron, given that it was supplied enough energy?

Note: This question excludes natural decay processes, such as electron capture.

REPLY [1 votes]: Does this idea of proton-to-neutron only apply to protons in the nucleus, free protons, or both?

Yes it is for both nuclear protons and free protons.
If this is the case, would accelerating a proton fast enough (causing a gain 1.29 MeV of energy) cause it to convert into a neutron? If so, has this been done before? And was it done with free protons or protons in the nucleus?

It can be done by the absorption of a W- boson because only weak interactions are flavor changing.
It cant be done by the absorption of a pion because in strong interactions -topness and  downness is conserved . 
I'm familiar with the Cowan-Reines experiment and how antineutrinos were used to convert protons to neutrons. Are we limited only to antineutrinos to cause such a transformation? Or could any elementary particle (say, an electron) cause a proton to convert into a neutron, given that it was supplied enough energy?

Yes it can be done with antineutrinos and the emmited particle will be the type of neutrino . For example : If a muon antineutrino is absorbed by the proton , an antimuon will be created , if a tau antineutrino is absorbed by the proton , an antitau will be created to conserve lepton number.
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