The EXO-200 experiment reports on an improved measurement of the 2\nu \beta \beta\ half-life of Xe-136 performed by EXO-200. The use of a large and homogeneous time projection chamber allows for the precise estimate of the fiducial mass used for the measurement, resulting in a small systematic uncertainty. We also discuss in detail the data analysis methods used for double-beta decay searches with EXO-200, while emphasizing those directly related to the present measurement. The Xe-136 2\nu \beta \beta\ half-life is found to be 2.172 +- 0.017 (stat) +- 0.060 (sys) x 10^21 years. This is the most precisely measured half-life of any 2\nu \beta \beta\ decay to date.
Dr. Bruce Cleveland, a SNOLAB research scientist is also a member of the EXO-200 Collaboration.
Full paper attached below.