Chemistry Department Colloquium

After the first direct observation of neutrino flavor transformations at the Sudbury Neutrino Observatory, future planned neutrino experiments are focusing on the understanding of the neutrino oscillation mechanism by determining key neutrino parameters, such as the mass differences and mass hierarchy, the mixing angles, and the possibility of CP violation. Organic liquid scintillators (LS) have been the detection medium of choice for neutrinos since the early discovery experiment of Reines and Cowan. For the delayed neutron-capture signal, the advantages of adding a metal element to the LS (to form M-LS) are significant. Chemically, there are challenges to adding inorganic salts of metal, such as directly to the LS. Key aspects of the metal-loaded LS (M-LS) for neutrino detection are (a) long-term chemical stability, (b) high optical transparency, (c) high photon production by the LS, and (d) ultra-low impurity content, mainly of natural radioactive contaminants, such as U, Th, Ra, and Rn. BNL Neutrino & Nuclear Chemistry group holds a long history of neutrino research since Ray Davis’s pioneering Homestake experiment and has developed new chemical techniques of loading metals, such as In, Yb, Gd, Nd, and currently Li and Ca, in organic liquid scintillator that can be used for low-energy solar neutrino, reactor neutrino, or double-beta decay experiments. The chemical-doping technologies and the performance of different organometallic liquid scintillators for different experiments will be discussed.