Search for the double beta decay of Zr-96 with NEMO-3 and calorimeter development for the SuperNEMO experiment

• Main Author: Kauer, M. B.
• Published: University College London (University of London) 2010
• Subjects: 500
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.564944

Using 9.4 g of Zr-96 and 1221 days of data from the NEMO-3 detector corresponding to 0.031 kgy, the obtained 2vbb decay half-life measurement is [2.35 \pm 0.14(stat) \pm 0.16(syst)] \times 10_{19}yr. Different characteristics of the final state electrons have been studied, such as the energy sum, individual electron energy, and angular distribution. The 2v nuclear matrix element is extracted using the measured 2vbb half-life and is 0.049 \pm 0.002. The 0vbb decay half-life is excluded at the 90% CL to > 9.2 \times 10_^{21}yr corresponding to a limit on the effective Majorana neutrino mass of < 7.2 – 19.4 eV. Limits on other mechanisms of 0vbb have also been set. Due for commissioning in 2012, SuperNEMO is the next generation detector which improves upon the proven technology and success of NEMO-3 to achieve a half-life sensitivity of ~10_{26} yr (90% CL) for Se-82 which corresponds to a neutrino mass of 50-100 meV. An energy resolution of 7% FWHM at 1 MeV has been obtained for the calorimeter baseline design of SuperNEMO which is currently in the R&D phase. This result not only meets the requirement stipulated by the R&D proposal, but is unprecedented for this type of calorimeter design.