Calcium 48 is a rare isotope of calcium. 0.187% of natural calcium is calcium 48. Its half life is very long, so it is usually considered stable. It is unusually neutron-rich for such a light element, and the reason is that it is "doubly magic" in that it has 20 protons and 28 neutrons, and both 20 and 28 are magic numbers.

Ca-48 has been used to make ununquadium by bombarding targets of plutonium 244 by beams of calcium 48, accelerated in a particle accelerator. It is used for this purpose because it is a very stable and very neutron rich nucleus, and one problem in making superheavy nuclei like ununquadium is putting enough neutrons in their nucleus. Also, Calcium 48 is a good candidate in the search for neutrino-less double beta decay since it has the highest Q-value of 4.27 MeV among beta-beta-decaying isotopes. However, its low abundance so far prevented studies with large amounts.

Isotopes