Double Beta Decay

Double beta (ββ) decay is a rare transition between two nuclei with the same mass number that changes the nuclear charge number by two units. It has been long recognized as a powerful tool for the study of lepton conservation in general and of neutrino properties in particular. Because the lifetimes of ββ decay are so long, the experimental study of ββ decay is particularly challenging and has spawned a whole field of experiments requiring very low background.