Precision Measurement of Solar ν Fluxes with Borexino and Prospects for 0νββ Search with 136Xe-loaded Liquid Scintillators

After its successful Phase-I (2007-2011), Borexino has further improved its unprecedentedly low background and has entered the solar neutrino precision measurement era. Thanks to the developments in the data analysis and to a better understanding of the detector response, a global analysis of Borexino Phase-II data (2011-2016) was carried out, yielding to the simultaneous determination of 7Be, pep and pp neutrino fluxes. This PhD thesis describes the achievements (mainly regarding an improved simulation of the experiment) which made these accurate measurements possible. Furthermore, a more long term future for a Borexino-like experiment hunting for neutrinoless double beta decay (0νββ) is discussed. The current status of uncertainties and experimental/theoretical expectations on 0νββ is summarized, and the possible sensitivity of a large, next generation 136Xe-loaded liquid scintillator detector is assessed and compared to present and near future experiments. The results of the experimental investigations of optical properties of liquid scintillators loaded with xenon at high pressure are also presented, in view of possible future applications.