A Comment on the Measurement of Neutrino Masses in Beta-Decay   Experiments
  We discuss the physics potential of future tritium beta-decay experiments having a sensitivity to a neutrino mass ~\sqrt{|\Delta m^{2}_{23}|}~5x10^{-2} eV. The case of three-neutrino mixing is analised. A negative result of such an experiment would imply that the neutrino mass spectrum is of normal hierarchical type. The interpretation of a positive result would depend on the value of the lightest neutrino mass; if the lightest neutrino mass satisfies the inequality min(m_j) << \sqrt{|\Delta m^{2}_{23}|}, it would imply that the neutrino mass spectrum is of the inverted hierarchical type. 
S. M. Bilenky, M. D. Mateev and S. T. Petcov