Observation of Two-Neutrino Double-Beta Decay inXe136with the EXO-200 Detector

• DOI: 10.1103/physrevlett.107.212501
• Publication Date: 2011-11-17T22:49:16Z
• Authors: N. Ackerman; B. Aharmim; M. Auger; D. J. Auty; P. S. Barbeau; K. Barry; L. Bartoszek; E. Beauchamp; V. Belov; C. Benitez-Medina; M. Breidenbach; A. Burenkov; B. Cleveland; R. Conley; E. Conti; J. Cook; S. Cook; A. Coppens; I. Counts; W. Craddock; T. Daniels; M. V. Danilov; C. G. Davis; J. Davis; R. deVoe; Z. Djurcic; A. Dobi; A. G. Dolgolenko; M. J. Dolinski; K. Donato; M. Dunford; W. Fairbank; J. Farine; P. Fierlinger; D. Franco; D. Freytag; G. Giroux; R. Gornea; K. Graham; G. Gratta; M. P. Green; C. Hägemann; C. Hall; K. Hall; G. Haller; C. Hargrove; R. Herbst; S. Herrin; J. Hodgson; M. Hughes; A. Johnson; A. Karelin; L. J. Kaufman; T. Koffas; A. Kuchenkov; A. Kumar; K. S. Kumar; D. S. Leonard; F. Leonard; F. LePort; D. Mackay; R. MacLellan; M. Marino; Y. Martin; B. Mong; M. Montero Díez; P. Morgan; A. R. Müller; R. Neilson; R. Nelson; A. Odian; K. O’Sullivan; C. Ouellet; A. Piepke; A. Pocar; C. Y. Prescott; K. Pushkin; A. Rivas; E. Rollin; P. C. Rowson; J. J. Russell; A. Sabourov; D. Sinclair; K. Skarpaas; S. Slutsky; V. Stekhanov; V. Strickland; M. Swift; D. Tosi; K. Twelker; P. Vogel; J.-L. Vuilleumier; J.-M. Vuilleumier; A. Waite; S. Waldman; T. Walton; K. Wamba; M. Weber; U. Wichoski; J. Wodin; J. D. Wright; L. Yang; Y.-R. Yen; O. Ya. Zeldovich
• Keywords: 550; 0103 physical sciences; 530; 01 natural sciences

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.