  We propose an ansatz, named the "particle ansatz", that in the rest frame of
a flavor neutrino all its mass eigenstate momentums should simultaneously be
zero. Under the particle ansatz, the mass measurable phase differences (mmPhDs)
can be derived as $\Delta\phi_{ji}\simeq [2m_{\nu_\alpha}(m_j-m_i)/4
E_{\nu_\alpha}]L$. We show that using mmPhDs all three neutrino masses can be
determined. In the foreseeable future all neutrino masses are expected to be
determined by the spectral analysis of neutrino experiments.
