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T: Fachverband Teilchenphysik
T 139: Neutrinos VI
T 139.6: Talk
Thursday, March 23, 2023, 18:30–18:45, POT/0051
CNO solar neutrinos measurement with Borexino detector: updated combined analysis with directionality constraint — •Luca Pelicci — Forschungszentrum Jülich GmbH, Institut für Kernphysik IKP-2, Jülich, Germany — Johanniterstrasse 22
Borexino was a large liquid scintillator experiment with an unprecedented level of radiopurity, designed for real-time detection of low-energy solar neutrinos. It was located at the underground INFN Laboratori Nazionali del Gran Sasso, in Italy. During more than ten years of data taking, it has measured the neutrino flux from each individual within the proton-proton-chain, i.e. the main fusion process accounting for 99 % of the energy production of the Sun, and in the CNO cycle, responsible for the remaining 1%. To disentangle neutrino-induced signals from residual background, a multivariate analysis was adopted, based on the fitting of the spectrum of Borexino events with Monte-Carlo simulated reference shapes. In recent years, through the method called "Correlated and Integrated Directionality" (CID) Borexino has also provided a proof of principle for the exploitation of the sub-dominant Cherenkov information produced by sub-MeV solar neutrinos in a liquid scintillator detector. In this talk, the improvements and upgrades performed in recent years will be discussed. Furthermore, the combination of the two analysis approaches was recently exploited for a measurement of the CNO solar neutrinos with improved precision. The most recent results will be presented.