  It has been suggested that the reported temporal oscillations in the weak
decay of H-like ions circulating in the GSI storage ring may be accounted for
by interference between two different momentum components of the wave function
of the parent ions. In that model, the interference is said to come about
through coupling of those two momentum components to the two mass components in
the wave function of the electron neutrino in the decayed state. I show here
that quantum mechanics allows no such interference to contribute to the
reported oscillation of the decay rate. The central issue is that the storage
ring is a million times too small to allow the parent ion's wave function to
produce the needed interference effect. This note supersedes earlier arXiv
postings that were less general and less rigorous.
