SNO, with its sensitivity to detect all three types, will check on this theory. We do not know whether they have a mass or whether they are little bundles of energy with no mass, always moving at the speed of light. It should also be able to capture the three known types of neutrinos. Finally, the receiver must be interfaced to instruments and computers that can record what happens so that scientists can study the interactions in detail. But looks can be deceiving.
Neutrino observatories are at the very cutting edge of research in physics and astronomy.
The key to the Sudbury observatory is the availability of pure heavy water. No other country in the world has available reserves of large amounts of heavy water sufficient for a neutrino observatory. It is not radioactive and is the same as ordinary water except that it has a neutron, in addition to a proton in the nucleus of each hydrogen atom in the water. Heavy water is the ideal medium for detecting neutrinos because all three types of neutrinos react with it. About 7,000 neutrinos a year are expected to interact with nuclei of atoms in the 1,000 tonnes of heavy water in the observatory's giant acrylic container.