Würzburg 2018 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 68: Neutrinophysik III

T 68.5: Vortrag

Mittwoch, 21. März 2018, 17:30–17:45, Z6 - SR 2.012

Rejection of the cosmogenic ¹¹C background in the Borexino detector for the observation of the neutrino flux from CNO chain in the sun — •Alessio Porcelli for the Borexino collaboration — Johannes Gutenberg Universität, Mainz, Deutschland

Borexino is a liquid scintillator detector sited underground in the Laboratori Nazionali del Gran Sasso. Its physics program is centred in the study of solar neutrinos. Recently, a simultaneous spectroscopy was performed for the neutrinos from the pp, pep and ⁷Be fusion reactions, together with a new analysis of the νs from the ⁸B chain. The next goal of the Borexino solar program is to improve the current lower limit of the neutrino flux from the CNO cycle, or possibly measure it for the first time. This result will greatly improve the understanding of the Solar Standard Model. The main limitation of this measurement is the ¹¹C cosmogenic background produced from ¹²C nuclei by muon induced spallations with emission of neutrons: the physics of this process is not very well understood and ¹¹C has a long average decay time (half hour), therefore its direct identification and prediction is not possible. The Borexino analysis approach to deal with this background is called Three Fold Coincidence (TFC) and relies on time and space coincidence of muons and neutrons, vetoing volumes where those associated signatures occurred and might contain ¹¹C. In this work it is presented an overview of the TFC and studies performed to improve its efficiency, including a complementary method that take advantage of possible productions of multiple ¹¹C by the same muon.