Observation of two-neutrino double-beta decay in 136Xe with the EXO-200 detector.


We report the observation of two-neutrino double-beta decay in (136)Xe with T(1/2) = 2.11 ± 0.04(stat) ± 0.21(syst) × 10(21) yr. This second-order process, predicted by the standard model, has been observed for several nuclei but not for (136)Xe. The observed decay rate provides new input to matrix element calculations and to the search for the more interesting neutrinoless double-beta decay, the most sensitive probe for the existence of Majorana particles and the measurement of the neutrino mass scale.

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@article{Ackerman2011ObservationOT, title={Observation of two-neutrino double-beta decay in 136Xe with the EXO-200 detector.}, author={Nathanael Leedom Ackerman and B . Aharmim and Martin Auger and David Auty and P S Barbeau and Killian Barry and Larry M. Bartoszek and Elspeth M. Beauchamp and V . A . Belov and C. Benitez-Medina and Martin Breidenbach and Alexander Burenkov and B . T . Cleveland and Ray Conley and Enrico Conti and John A. Cook and Steffan Cook and Ann Coppens and Ian Counts and W. C. Craddock and Thomas L. Daniels and M. V. Danilov and Clayton G. Davis and Justin D. Davis and R . DeVoe and Z. Djurcic and Attila Dobi and A . G . Dolgolenko and Miroslaw Dolinski and Karim Donato and Monica Dunford and William Fairbank and J . Farine and Peter Fierlinger and D . Torres - Franco and David Freytag and Gaston Giroux and R . Gornea and Kimmer Graham and Giorgio Gratta and M. P. Green and C. Haegemann and Christina Hall and Kathleen B. Hall and George Haller and C . K . Hargrove and Ryan Herbst and S. Herrin and Jennifer Hodgson and Mikayla Hughes and Anthony Johnson and Alexey Karelin and Laura J. Kaufman and Th . Koffas and A . Kuchenkov and Ankit Kumar and K . santhosh Kumar and D . S . Leonard and F. Leonard and F Leport and Doug Mackay and R . MacLellan and Mark G Marino and Yves-Armel Martin and B . Mong and M. Montero Diez and Paul M Morgan and Andrea M{\"{u}ller and Robert H. Neilson and Richard Alan Nelson and A . C . Odian and Kyra O'Sullivan and Claudine Ouellet and Andreas Piepke and Andrea Pocar and Charles Y. Prescott and Kirill Pushkin and {\'A}ngel Rivas and Etienne Rollin and P . C . Rowson and John J. Russell and A . V . Sabourov and Donald Keith Sinclair and Knut Skarpaas and Simon Slutsky and V . N . Stekhanov and V . Strickland and Margaret Swift and D . Tosi and Kaja Twelker and Petr Vogel and J . - M . Vuilleumier and J . - L . Vuilleumier and A . P . Waite and Samuel J Waldman and T . Walton and Kanzi Wamba and Michel Weber and Ubirajara F. Wichoski and J . Wodin and Jay Wright and Li Yang and Y-R Yen and O Ya Zeldovich}, journal={Physical review letters}, year={2011}, volume={107 21}, pages={212501} }