neutretton.

1938 N. Arley & W. Heitler in Nature 23 July 159/1 Neutrons would have a much smaller penetrating power and there is no process known by which neutrinos could produce heavy electrons in sufficiently large numbers. We therefore think that we have to deal in these experiments with the neutral counterpart of the heavy electron, for which we propose the name neutretto.

1947 Sci. News 4 123 A neutral meson is also expected to appear; the romantic name Neutretto is ready waiting for it.

1948 Rev. Mod. Physics 20 550/1 If the neutral particle is a neutrino, the electron energy should be almost exactly one-half the rest energy of the meson, i.e., 50 Mev. If the neutral particle is considerably heavier than an electron (neutretto) the energy of the decay electron should be correspondingly smaller.

1952 R. E. Marshak Meson Physics vi. 208 If one is willing to consider the possibility of a new neutral decay particle of small rest mass (we shall call it a neutretto and denote it by μ⁰), then an alternative decay scheme would be μ^± → e^± + ν + μ⁰.

1963 New Scientist 1 Aug. 255 The terms ‘electron neutrino’ and ‘muon neutrino’ respectively for ‘neutrino’ and ‘neutretto’ are probably more common at present in distinguishing these two particles.

1979 Science 5 Jan. 15/3 Why should the neutral particle (or ‘neutretto’ as it was first called) produced in the decay of a pion to a muon..be the same as the neutrino of nuclear beta decay?