The sensitivity of the NEMO technique to neutrinoless double beta decay and the commissioning of the SuperNEMO demonstrator module

Abstract

The SuperNEMO Demonstrator Module is currently being commissioned at the LSM in Modane France. Its aim is to search for neutrinoless double beta decay (0νββ) with a half-life sensitivity of 4 × 10^24 years at 90% CL with an exposure of 17.5 kg.yr of the isotope ^82Se and a background level of < 10^−4 events/(keV.kg.yr). This corresponds to an effective Majorana neutrino mass limit of < (260 − 500) meV. SuperNEMO has a unique ability to measure the full topology of double beta-like events using its separated tracker-calorimeter design. Commissioning tasks for the calorimeter and tracker are presented. The quality of the SuperNEMO PMT pulse shapes is investigated and a novel approach to measuring the PMT time resolution is developed. The model development, experimental design and analysis techniques for a study into the effects of helium poisoning on the R5912-MOD Hamamatsu PMT is summarised and the practical implications of the study with respect to SuperNEMO are discussed. Initial data quality checks of the tracker commissioning data and example event maps are also presented. The next generation of 0νββ experiments aim to achieve a half-life sensitivity on the order of 10^28 years. A sensitivity study is presented to describe the outlook for the NEMO measurement technique in matching the sensitivity goals of these discovery type detectors

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