Electron Capture b-Decay Recoil Energies and the Sterile Neutrino Mass.New Submission

We study the dependence of atomic recoil energies on the neutrino rest mass in electron capture b-decays. Two situations are considered: 1) an unstable nucleus absorbs an atomic electron and transitions to the ground state of the daughter atom radiating a neutrino, and 2) the nucleus first absorbs an atomic electron and transitions to an excited state of the daughter atom radiating a neutrino, and then transitions to the ground state radiating a photon. We show that the energy difference DE between the recoil energies in the two decay channels may indicate radiation of a sterile neutrino. Experimental study of the energy difference DE could be used for the search of sterile neutrinos.