  We consider a quantum field theory (QFT) model of neutrino oscillations in
vacuum that attempts to take into account that the neutrino source particle and
the neutrino detection particle both interact with their respective
environments by collisions. Our model is minimal in a twofold sense. Firstly we
simply assume that neutrino production and detection take place in between
collisions in time intervals $\Delta t$ and $\tau$, respectively. Secondly, we
only introduce the two wave packets that are absolutely necessary which are
those of the neutrino source and the neutrino detection particle. Within this
model we find that, for all practical purposes, there are no decoherence
effects in the neutrino oscillation amplitude and oscillations occur in space
not in time. Moreover, our model leads to the correct time correlation between
neutrino production and detection and to a factorization of the event rate of
the compound neutrino production--detection process into decay rate,
oscillation probability and detection cross section.
