An Improved ZnMoO4 Scintillating Bolometer for the Search for Neutrinoless Double Beta Decay of 100Mo
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We present a prototype scintillating bolometer for the search for neutrinoless double β decay of 100Mo, consisting of a single ≈5 g ZnMoO4 crystal operated aboveground in the 20–30 mK temperature range. The scintillation light is read out by two thin Ge bolometers. The phonon signals are collected by NTD Ge thermistors. The ZnMoO4 crystal was grown with an advanced method (low-thermal-gradient Czochralski technique) and after purification of molybdenum. The results are very encouraging: the intrinsic energy resolution of the heat channel is ≈800 eV FWHM, the α/β rejection factor (crucial for background suppression) is better than 99.9% in the region of interest for double β decay (≈3 MeV), and the radiopurity of ZnMoO4 looks substantially improved with respect to previous devices.
KeywordsDouble beta decay Neutrino mass Low background Bolometric technique ZnMoO4 crystals
The work of F.A. Danevich was supported by a Cariplo Foundation fellowship organized by the Landau Network—Centro Volta (Como, Italy). The group from the Institute for Nuclear Research (Kyiv, Ukraine) was supported in part through the Project “Kosmo-mikrofizyka-2” (Astroparticle Physics) of the National Academy of Sciences of Ukraine. The light detectors have been realized within the project LUCIFER, funded by the European Research Council under the EU Seventh Framework Programme (ERC grant agreement No. 247115).