Detecting warm DM in the $MeV/c^2$ range
  Some tension exists between present experimental data and models which
comprise only the three light neutrino mass eigenstates necessary to explain
solar and atmospheric oscillation results. Hence the revival of the idea that
additional more massive states might enter the active neutrino superpositions
produced and observed in charged current reactions. Such 'heavy' neutrinos with
masses in the keV or MeV range might also be of interest as dark matter
candidates. A state with mass larger than 1022 keV could decay into an $e^+
e^-$ pair and a light mass state, leaving an easily recognizable signature. The
aim of this paper is to estimate the possible signal rate.
