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., September 22, 2011, at 3:00 p.m. (refreshments at 2:40 p.m.)

Observation of Two-Neutrino Double-Beta Decay in 136Xe with EXO-200

Liang Yang, SLAC National Accelerator Laboratory, Menlo Park, CA
Building 6008 Conference Room

The Enriched Xenon Observatory (EXO) is an experimental program designed to search for the neutrinoless double-beta decay of 136Xe. The current phase of the experiment, EXO-200, uses 200 kg of liquid xenon with 80% enrichment in 136Xe, and also serves as a prototype for a future 1-10 ton scale EXO experiment. The detector has been taking low background physics data with enriched xenon at Waste Isolation Pilot Plant (WIPP) in New Mexico since early May 2011. After performing the first charge only analysis of the data, we report the observation of two-neutrino double-beta decay in 136Xe with T1/2 = 2.11 ± 0.04 (stat.) ± 0.21 (sys.) x 1021 years. This second order process, predicted by the Standard Model, has been observed for several nuclei but not for 136Xe. The observed decay rate provides new input to matrix element calculations and to the search for the more interesting neutrinoless double-beta decay mode.