  Neutrino-nucleus elastic scattering provides a unique laboratory to study the
quantum mechanical coherency effects in electroweak interactions, towards which
several experimental programs are being actively pursued. We report results of
our quantitative studies on the transitions towards decoherency. A parameter
($\alpha$) is identified to describe the degree of coherency, and its
variations with incoming neutrino energy, detector threshold and target nucleus
are studied. The ranges of $\alpha$ which can be probed with realistic neutrino
experiments are derived, indicating complementarity between projects with
different sources and targets. Uncertainties in nuclear physics and in $\alpha$
would constrain sensitivities in probing physics beyond the standard model. The
maximum neutrino energies corresponding to $\alpha$>0.95 are derived.
