Bolometric measurements of beta decay spectra of Re-187 with crystals of silver perrhenate

Crystals of silver perrhenate were used for the first time in the bolometri c measurement of the spectrum of Re-187 with the aim of determining the ele ctron antineutrino mass. The temperature rise was measured by means of neut ron transmutation doped germanium and P-implanted silicon thermistors. The energy scale was calibrated using the K lines of Mn and the fluorescence L lines of Sn. Bolometers made from crystals of masses ranging from similar t o 250 to similar to 500 mu g were run with FWHM resolutions on the Sn lines ranging from 25 to 60 eV. The end point of the spectrum was located at 246 0 +/- 5(stat) +/- 10(syst) eV. The measured half lifetime was 43 +/- 4(stat ) +/- 3(syst) Gyr, which is in good agreement with the values obtained with mass spectroscopy from the build-up of Os-187 in rhenium samples. The sens itivity of the measurement on a non-zero neutrino mass achievable with thes e bolometers is discussed. (C) 1999 Published by Elsevier Science B.V. All rights reserved.