  This work considers the following problem: what type (Dirac or Majorana) of
neutrinos is produced in standard weak interactions? It is concluded that only
Dirac neutrinos but not Majorana neutrinos can be produced in these
interactions. It means that this neutrino will be produced in another type of
interaction. Namely, Majorana neutrino will be produced in the interaction
which differentiates spin projections but cannot differentiate neutrino
(particle) from antineutrino (antiparticle). This interaction has not been
discovered yet. Therefore experiments with very high precision are important to
detect the neutrinoless double decay.
