# UCL Discovery

## Search for the neutrinoless double beta decay of 100Mo with the NEMO3 detector and calorimeter research and development for the SuperNEMO experiment

Basharina-Freshville, A.; (2012) Search for the neutrinoless double beta decay of 100Mo with the NEMO3 detector and calorimeter research and development for the SuperNEMO experiment. Doctoral thesis, UCL (University College London).

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## Abstract

The world’s most precise half-life measurement of T^2nu_1/2 = [7.02 ± 0.01(stat) ± 0.46(syst)] × 10^18 years has been made for the 2\nu\beta\beta decay of ^100Mo using data from 6.9kg collected with the NEMO3 detector over 1471 days. The 2\nu nuclear matrix element has been extracted using T^2nu_1/2 and is M^2\nu = 0.126 ± 0.004. The 0\nu\beta\beta search yielded a limit on the half-life of T^0\nu_1/2 1/1 > 1.1 × 10^24 years at the 90% CL, corresponding to a limit on the effective Majorona mass of \langle M\nu e\rangle < 0.3 - 1.0eV, one of the most stringent constraints on \langle M\nu e\rangle in the world. Limits on the right-handed currents and Majoron 0\nu\beta\beta modes have also been set. The world’s most stringent bound has been set on the Majoron to neutrino coupling constant of \langle g \chi o \rangle < (0.2 − 0.7) × 10^−4. SuperNEMO is a next generation \beta\beta decay experiment, based on the design and experience of NEMO3. Due to start demonstrator operation in 2013, SuperNEMO aims to achieve a sensitivity of 10^26 years, corresponding to \langle M\nu e\rangle < 50-100meV using ^82Se. An alternative to the baseline calorimeter design was considered, using 2m x 10cm x 2.54cm scintillator bars. An energy resolution of 10% FWHM at 1 MeV and a time resolution of ~ 450ps was achieved for the alternative design. This is an unprecedented energy resolution for a scintillator of this size.

Type: Thesis (Doctoral) Search for the neutrinoless double beta decay of 100Mo with the NEMO3 detector and calorimeter research and development for the SuperNEMO experiment An open access version is available from UCL Discovery English The abstract contains LaTeX text. Please see the attached pdf for rendered equations UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Physics and Astronomy