Limits on neutrinoless double beta decay in 136Xe with a time projection chamber

Abstract A xenon Time Projection Chamber with an active volume of 207 liters has been built to study 0ν and 2ν double beta decay in 136 Xe. Data were taken in the Gotthard Underground Laboratory, with 5 atm of xenon enriched to 62.5% in 136 Xe. From 4861 hours of data, no evidence has been found for the 0 + → 0 + transition. Half-life limts of T 1 2 0ν (0 + → 0 + ) > 2.7(5.2) × 10 23 years in the mass mechanism mode, and T 1 2 0ν (0 + → 0 + ) > 1.9(3.5) × 10 23 years in the right-handed currents mode, at the 90(68)% C.L., were derived. Upper limits for the Majorana neutrino mass parameter were deduced.