Study of the neutrino mass in a double β decay
Zel'dovich Ya. B., Khlopov M. Yu.
Experiments on the search for the 2β decay, which can yield unique information on the presence of a Majorana mass in a neutrino and a possible nonconservation of lepton number are proposed. A search for 2β + decays is especially promising in view of the possibility of a pure isolation of the coincidence signal of four annihilation /-ray quanta.