Search for Majorana neutrino - a problem for atomic physics

The nuclear way to discover Majorana neutrinos is the neutrinoless ββ decay. An alternative is offered by the inverse process, neutrinoless radiative double electron capture accompanied by a photon emission. Two different mechanisms seem plausible: the magnetic type radiation by an initial 1S electron and the resonant electric type radiation by the final atom. The latter poses an interesting and nonconventional problem in the atomic research.