Status and perspectives of the Mainz neutrino mass experiment

Abstract The Mainz measurement in 1994 is discussed in the view of the problem of “negative m ν 2 ” obtained in the analysis for larger energy intervals below the endpoint of the β spectrum. A possible explanation due to a roughening transition of the T 2 film is given. The very recent improvement of the Mainz setup and a first 4 weeks measurement is presented. An outlook to the perspectives of the present setup and into the future is given.