Measurement of absolute light yield and quantum efficiency of LaBr3:Ce scintillator detector using SiPM

This brief communication presents our work to determine the absolute light yield and quantum efficiency of LaBr3:Ce scintillator by comparison and also by direct pulse measurement method using SiPM. The first part presents use of the simpler comparison method to determine the light yields of different scintillators using the known yield of NaI(Tl) as reference. In the second part we have determined the absolute light yield and quantum efficiency of LaBr3:Ce crystal by using a SiPM photo detector. Our measured value is in good agreement with the light yield reported by previous measurements using PMT and excitation fluorescence spectroscopy. Quantum efficiencies for scintillation detectors have been determined by using both PMTs and photo detectors, namely APDs by previous authors. This communication is possibly the first report on the determination of quantum efficiency of LaBr3:Ce using SiPM photo detector. The simple and effective method presented here would allow to determine the light yield of any scintillation detector.

Borexino Results on Neutrinos from the Sun and Earth

Borexino is a 280-ton liquid scintillator detector located at the Laboratori Nazionali del Gran Sasso in Italy. Since the start of its data-taking in May 2007, it has provided several measurements of low-energy neutrinos from various sources. At the base of its success lie unprecedented levels of radio-purity and extensive thermal stabilization, both resulting from a years-long effort of the collaboration. Solar neutrinos, emitted in the Hydrogen-to-Helium fusion in the solar core, are important for the understanding of our star, as well as neutrino properties. Borexino is the only experiment that has performed a complete spectroscopy of the pp chain solar neutrinos (with the exception of the hep neutrinos contributing to the total flux at 10−5 level), through the detection of pp, 7Be, pep, and 8B solar neutrinos and has experimentally confirmed the existence of the CNO fusion cycle in the Sun. Borexino has also detected geoneutrinos, antineutrinos from the decays of long-lived radioactive elements inside the Earth, that can be exploited as a new and unique tool to study our planet. This paper reviews the most recent Borexino results on solar and geoneutrinos, from highlighting the key elements of the analyses up to the discussion and interpretation of the results for neutrino, solar, and geophysics.