Low background study of the neutrinoless double beta decay of 76-GE and upper limit for neutrino mass

A Ge detector system was built possessing significnt reduced background, from natural radioactivities, notably 208-TI (2.6 MeV line). After a 2600 h measuring period a lower limit for the half life of the neutrinoless double beta decay in 76- Ge of T( {1}/{2}oν) > 1.7 × 10 22yr (1σ) was obtained, corresponding to a neutrino mass upper limit of 22 eV.