New limits from the Milano neutrino mass experiment with thermal microcalorimeters

In the Standard Model of electroweak interactions an important input parameter is still missing: the absolute value of the mass of one of the neutrinos. In this paper we report the final results of the Milano electron anti-neutrino mass experiment after having measured for about one year the beta spectrum of Re-187 with 10 AgReO4 microcalorimeters. We describe the experimental set-up, the detector performance and the measuring conditions. We present the updated limit on the electron anti-neutrino mass which is the most stringent so far obtained with thermal detectors. We also give the most precise estimates for the Re-187 transition energy and lifetime. (C) 2003 Elsevier B.V. All rights reserved.