Date and Time: Monday, 20 November 2017, at 12:00 AM

Venue: Conference Hall, Dzhelepov Laboratory of Nuclear Problems

Seminar topic: «Investigation of the bb-decay processes of ⁸²Se with SuperNEMO detector»

Speaker: O.I. Kochetov

Abstract:

SuperNEMO is a double beta decay experiment based on the successful tracking plus calorimetry technology of the NEMO-3 experiment. The goal of NEMO-3 was to the search for neutrinoless double beta decay (0vββ) and accurate measurements of the two-neutrino double beta decay (2vββ). The detector was installed at the Laboratoire Souterrain de Modane (LSM) and studied ββ-decays of seven isotopes between 2003 and 2011. Its unique approach based on a combination of a calorimetric and a tracking measurements allows for a full reconstruction of the ββ-events topology with a very low background level. This feature also permits other exotic searches such as investigation of hypothetical quadruple beta decay (0v4β). The latest results from NEMO-3 concerning the ¹¹⁶Cd and ¹⁵⁰Nd isotopes are presented as well as the installation status of the first SuperNEMO module – the Demonstrator.
The SuperNEMO goal is to search for 0vββ-decays of 100 kg of ⁸²Se with a sensitivity of T1/2 ~ 10²⁶ y corresponding to < (0.04 – 0.10) eV. After an extended R&D program to improve the detector design and its radiopurity, the construction of the first module, called the Demonstrator, is approaching its completion at LSM.
The SuperNEMO Demonstrator has a broad physics program. The key goal is to demonstrate that this technology can reach extremely low background levels (below 10^-4 events/keV/kg/y in the region of interest) and therefore can be extrapolated to 100’s of kilograms of isotope. The Demonstrator itself will reach a sensitivity of 6 x 10²⁴ y to 0vββ decay of ⁸²Se after 2.5 y of data taking and will also search for ββ-decay to excited states. In addition, the SuperNEMO Demonstrator will use its unique capability of reconstructing individual tracks and energies of electrons emitted in ββ-decay to make precise measurements of 2vββ of ⁸²Se and attempt to resolve a number of long standing questions posed by nuclear models, such as quenching of gA and single intermediate state versus higher intermediate states dominance, thus providing direct input into nuclear matrix element calculations. Moreover, reconstruction of individual electron energies and angular correlations will allow SuperNEMO to search for new physics outside of the ββ-decay domain, such as violation of Lorentz invariance, neutrino bosonic component, time variation of the Fermi coupling constant. Finally, the ability of the SuperNEMO technology to investigate ββ-decay of almost any isotope will be explored should the enrichment of other isotopes, especially those with high Qββ values such as ¹⁵⁰Nd and ⁴⁸Ca, become feasible.