The 136Xe double-beta-decay track experiment

Abstract A detector for studying the 136 Xe 2β-decay with a proportional drift chamber of volume V = 13 m 3 and operating with 10 kg of 136 Xe is considered. A limit of T 1 2 (2β0ν) > 10 23 yr can be reached at the sea level. The invesigation of background with a prototype (size (1.0×0.8×0.4) m 3 and 136 Xe mass 0.5 kg) showed that the track information allows a high background-rejection coefficient (> 10 6 ). The technique proposed in this article allows the defining of the admixture of 222 Rn in the working gas at a level of 10 −20 −10 −21 atom/atom. A half-life limit of T 1 2 (2β2ν) > 2×10 19 yr (90% CL) was obtained.