Search for Neutrinoless Double-Beta Decay in $^{136}$Xe with EXO-200
  We report on a search for neutrinoless double-beta decay of $^{136}$Xe with EXO-200. No signal is observed for an exposure of 32.5 kg-yr, with a background of ~1.5 x 10^{-3} /(kg yr keV) in the $\pm 1\sigma$ region of interest. This sets a lower limit on the half-life of the neutrinoless double-beta decay $T_{1/2}^{0\nu\beta\beta}$($^{136}$Xe) > 1.6 x 10$^{25}$ yr (90% CL), corresponding to effective Majorana masses of less than 140-380 meV, depending on the matrix element calculation. 
M. Auger, D. J. Auty, P. S. Barbeau, E. Beauchamp, V. Belov, C.   Benitez-Medina, M. Breidenbach, T. Brunner, A. Burenkov, B...
hep-ex nucl-ex