| Nuclei which have both neutron number and proton (atomic) number equal to one of the magic numbers are called "doubly magic", and are especially stable against decay. Examples of doubly magic isotopes include helium-4 (4He), oxygen-16 (16O), calcium-40 (40Ca), calcium-48 (48Ca), nickel-48 (48Ni), nickel-56 (56Ni), tin-100 (100Sn), tin-132 (132Sn) and lead-208 (208Pb). It is no accident that helium-4 (4He) and oxygen-16 (16O) are the second and third most abundant (and stable) elements in the universe.
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| Both calcium-48 (48Ca) and nickel-48 (48Ni) are doubly magic because calcium-48 has 20 protons and 28 neutrons while nickel-48 has 28 protons and 20 neutrons. Calcium-48 is very neutron-rich for such a light element, but is made stable by being doubly magic. Similarly, nickel-48, discovered in 1999, is the most proton-rich isotope known.
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| In December 2006 hassium-270 (270Hs) was discovered by an international team of scientists led by the Technical University of Munich having the unusually long
half-life of 22 seconds. Hassium-270 evidently forms part of an island of stability, and may even be doubly magic.
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See Also