“BOREXino” refers to an experiment performed by an international collaboration centered on solar neutrino physics.
Neutrinos are released in radioactive beta-decays, like what happens in the sun during nuclear fusion. Given the enormity of the sun, this would correspond to a flux of about 6.5 x 1010 neutrinos per square centimeter per second hitting the earth. However, neutrinos are notoriously difficult to detect and measure. Early experiments calculated far less (about 40%) neutrinos than predicted actually hitting the earth, and did not find significant variations with either day/night or season.
The Borexino detector, located underground in the Laboratori Naxioli del Gran Sasso in Italy, is a new look at this problem. It is capable of detecting low-energy solar neutrinos in real-time, and is capable of precisely measuring the beryllium solar neutrino flux and its day/night asymmetry – and its ultrapure scintillator (acting as a light concentrator) makes for some really cool pictures.
Learn more by checking out the official website for the Borexino Experiment, or check out an excellent introduction to Solar Neutrinos and Other Solar Oddities.
The Abstract 