LIMITS ON NEUTRINOLESS DOUBLE-BETA DECAY IN XE-136 WITH A TIME PROJECTION CHAMBER

A xenon Time Projection Chamber with an active volume of 207 liters has been built to study 0nu and 2nu double beta decay in Xe-136. Data were taken in the Gotthard Underground Laboratory, with 5 atm of xenon enriched to 62.5% in Xe-136. From 4861 hours of data, no evidence has been found for the 0+ --> 0+ transition. Half-life limts of T1/2(0nu)(0+ --> 0+) > 2.7(5.2) x 10(23) years in the mass mechanism mode, and T1/2(0nu)(0+ --> 0+) > 1.9(3.5) x 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.