The comprehensive geo-neutrinos measurement using the Borexino detector, published in Ref. [1], is briefly presented and discussed. Borexino is an ultrapure liquid scintillator detector located at the Gran Sasso National Laboratory in Italy, whose primary scientific goal is the real-time spectroscopy of low energy solar neutrinos. So far, Borexino is the only experiment to achieve an evidence for geo-neutrinos existence beyond a 5f significance level. In the following, the geo-neutrinos analysis from 3262.74 days data-taking between December 2007 and April 2019, the improved analysis techniques and optimized data selection, and the implications from the geological point of view will be discussed.

A comprehensive measurement of solar neutrino fluxes has been completed using the Borexino Phase-II data in an extended energy range. The measurement reports pp, 7Be and pep neutrino fluxes with the highest precision ever achieved, 8B with the lowest energy threshold, the first Borexino limit on hep neutrinos, as well as the best limit on CNO neutrinos. These results and their physics interpretations concerning the so-called solar metallicity puzzle and the electron-neutrino survival probability, as well as other highlights of the analysis, have been summarized in this talk.

Solar neutrinos have played a central role in the discovery of the neutrino oscillation mechanism. They still are proving to be a unique tool to help investigate the fusion reactions that power stars and further probe basic neutrino properties. The Borexino neutrino observatory has been operationally acquiring data at Laboratori Nazionali del Gran Sasso in Italy since 2007. Its main goal is the real-time study of low energy neutrinos (solar or originated elsewhere, such as geo-neutrinos). The latest analysis of experimental data, taken during the so-called Borexino Phase-II (2011-present), will be showcased in this talk—yielding new high-precision, simultaneous wide band flux measurements of the four main solar neutrino components belonging to the “pp” fusion chain (pp, pep, 7 Be, 8 B), as well as upper limits on the remaining two solar neutrino fluxes (CNO and hep).

The SOX (Short distance neutrino Oscillations with BoreXino) experiment aims to perform a resolutive measurement for testing the longstanding hypotesis of a sterile neutrino in the eV$^2$ mass scale. A very intense and well calibrated $^{144}Ce-^{144}Pr$ antineutrino source will be placed under the large size and very low background Borexino detector at Laboratori Nazionali del Gran Sasso in Italy. Borexino demonstrated a such energy and position resolution that the disappearance experiment can be performed and the short distance oscillations might be directly observed. In this paper an overview of the key elements of the experiment is given and the expected sensitivity to determine the sterile neutrino mass is shown.

Geo-neutrinos, electron anti-neutrinos produced in beta-decays of naturally occurring radioactive isotopes in the Earth, are a unique direct probe of our planet's interior. After a brief introduction of the geo-neutrinos' properties and of the main aims of their study, we discuss the features of a detector which has recently provided breakthrough achievements in the field, Borexino, a massive, calorimetric liquid scintillator detector installed at the underground Gran Sasso Laboratory. With its unprecedented radiopurity levels achieved in the core of the detection medium, it is the only experiment in operation able to study in real time solar neutrino interactions in the challenging sub-MeV energy region. Its superior technical properties allowed Borexino also to provide a clean detection of terrestrial neutrinos. Therefore, the description of the characteristics of the detected geo-neutrino signal and of the corresponding geological implications are the main core of the discussion contained in this work.

A monitoring and management system for the thermal environment inside the Borexino neutrino detector was developed and installed in order to reduce uncertainties in temperature determination and limit undesirable thermal couplings between the environment and Borexino's active sections. This strategy is bringing improved radioactive background conditions to the physics signal thanks to the reduced mixing taking place in the liquid scintillator. While equilibrium has not yet been reached, and fine-tuning is possible, the system has proven extremely effective at greatly stabilizing the detector while offering precise insight into its internal thermal conditions and transport. Numerical simulations have also been used to feed this empirical data into a global model, providing information into present and future thermal trends.