I have a question about current experimental findings on the status of the neutron N while contained within nuclear radius of a stable atom, say Helium-4. It is well known that the N will undergo beta(-) decay when it is free from a nucleus (takes ~ 14 minutes). But... My question is--do the two N in stable Helium-4 maintain a stable identity with no beta (-) decay or, do they exist as a continuous back-forth transformation of N <----> P mediated by mesons ? Thanks for any help. If you can point me to a peered reviewed citation where this question has been addressed that would be appreciated.