Nuclear Seminar - Veronika Palušová (7.4.2021)
Wednesday 7.4.2021 at 14:00, online
By: Jaroslav Staníček
Mgr. Veronika Palušová (UK Bratislava / CENBG, Université de Bordeaux):
Monte Carlo simulation of background in the SuperNEMO experiment
Investigation of neutrino properties is one of the most essential interests for particle physics and for better understanding of the evolution of Universe. Crucial missing information could be provided by the observation of neutrinoless double beta-decay (0νββ), a rare decay that violates total lepton number by two units which makes it forbidden in the Standard Model of particle physics. If observed, it would signal that neutrinos are their own antiparticles - Majorana particles - and they could be the key to the matter-antimatter asymmetry problem. SuperNEMO is a one-of-a-kind experiment searching for neutrinoless double beta decay in the Modane Underground Laboratory (LSM), the deepest laboratory in Europe. It utilizes a tracking approach by separating the source isotope from the detector, while combining tracker and calorimetry techniques to detect emitted electrons independently. This approach provides the means to discriminate different underlying mechanisms for the 0νββ decay by measuring the decay half-life and the electron angular and energy distributions.
This unique approach offers extremely good background rejection based on reconstruction of the topology of measured events. Backgrounds to SuperNEMO’s double beta decay measurements arise from events that mimic the topology of two electrons emitted from a common vertex in the source foil at energies up to the Qββ value of 82Se, 2995 keV. In order to design a system with the lowest possible background, there is a need for understanding individual background sources and estimation of each component. High energy γ-rays originating from de-excitations of radionuclides in 238U and 232Th decay chains and from neutron capture reactions can mimic 2e− events through their interaction in the source foil. The aim of this work is to estimate the background contributions from high energy gamma rays coming from the underground environment and from (n,γ) reactions that constitute a major source of background to almost all underground experiments