Oak Ridge National Laboratory

Physics Division

Physics Division Seminars

Physics Division Seminars bring us speakers on a variety of physics related subjects. Usually these are held in the Building 6008 large Conference Room, at 3:00 pm on the chosen day, but times and locations may vary. For more information, contact our seminar chairman,

Alfredo Galindo-Uribarri
Tel (Office): (865) 574-6124  (FAX): (865) 574-1268

Thu., November 20, 2003, at 3:00 p.m. (refreshments served at 2:30 p.m.)

Neutrino-less Double Electron Capture - a tool to search for Majorana neutrino

Z. Sujkowski, The Andrzej Soltan Institute for Nuclear Studies, Otwock/Swierk, Poland
Bldg. 6008 Conference Room

The possibility to observe the neutrino-less double b decay and thus to prove the Majorana nature of neutrino as well as provide a sensitive measure of its mass is a major challenge of today’s neutrino physics. As an attractive alternative we propose to study the inverse process, the radiative neutrino-less double electron capture, 0n2EC. The associated monoenergetic photon provides a convenient experimental signature. Other advantages include the favorable ratio of the 0n2EC to the competing 2n2EC capture rates as opposed to that of 0nb-b- to 2nb-b- and, very importantly, the existence of coincidence trigger to suppress the random background. Theses advantages partly offset the expected longer lifetimes for the 0n2EC process. Chances for this process are calculated. High Z atoms are strongly favored. A resonance enhancement of the capture rates is predicted at small energy release, DE, comparable to the 2P-1S atomic level difference. Away from the resonance, the rates depend only slowly on DE, in strong contrast with the 0nbb decays. This makes studies of decays to excited states in final nuclei feasible, thus enhancing chances of locating the resonances. Candidates for such studies are considered. The experimental feasibility is estimated and found highly encouraging.