The study of very low energy neutrinos requires a suppression of the natural radioactivity. This is what Borexino succeeded to achieve.
Search for low-energy neutrinos from astrophysical sources with Borexino Astroparticle Physics Volume 125, February 2021, 102509 [DOI: doi.org/10.1016/j.astropartphys.2020.102509] (Submitted 1 October 2019, Accepted 29 August 2020, Available online 1 September 2020) Abstract We report on searches for neutrinos and antineutrinos
Final results of Borexino phase-I on low-energy solar neutrino spectroscopy Phys. Rev. D 89:11 (2014 Jun 25), pp. 112007.1-112007.68 [doi:10.1103/PhysRevD.89.112007] (preprint on arXiv) Abstract Borexino has been running since May 2007 at the Laboratori Nazionali del Gran Sasso laboratory in