The experiment

From 2007 to 2021, the Borexino experiment performed a spectroscopic measurement of the solar neutrino flux. Due to the low energy threshold and the unprecedented level of radiopurity achieved in the liquid scintillator target, Borexino is able to cover the full energy range of the solar neutrino spectrum. By now, all spectral components originating from the solar proton-proton fusion chain have been measured, verifying the energy dependence of oscillation probabilities expected by the stanard MSW-LMA oscillation scenario. In 2020, Borexino provided first evidence of for the occurrence of the alternative CNO fusion cycle in the Sun. Moreover, Borexino has performed a measurement of the geoneutrino flux produced by beta-decays of radioactive isotopes embedded in the Earth’s crust and mantle.

The Borexino detector (Borexino Collaboration)

Mainz: Cosmogenic background reduction & directional reco

The group in Mainz is engaged in the directional reconstruction of solar neutrinos in Borexino. For this, we identify the faint Cherenkov cone superimposed to the much brighter scintillation signal. We have developed a new reconstruction method based on the superimposed hit patterns of many neutrino events, dubbed Correlated and Integrated Directionality (CID). The collaboration has shown this method to work on solar Be-7 neutrinos. We are currently implementing this method for a final CNO neutrino analysis where directionality will be used to discriminate directional solar neutrino signals from isotropic radioactive background (Bi-210 decays) in the scintillator.

Please contact Prof. Dr. Michael Wurm for Bachelor, Master and PhD theses.