Sn72

Sn72, or tin-72, is the designation for a tin nucleus with mass number 72 (Z = 50, N = 22). It would be an extremely neutron-deficient, proton-rich isotope and is not known to exist as a bound state.

In the system of tin isotopes, bound nuclei are observed mainly in the mass range around 112–124, with several stable isotopes in that region. An isotope as light as Sn-72 lies far from the valley of stability and is not expected to be bound. Nuclear models generally place such a nucleus beyond the proton drip line for tin, meaning that if formed, it would be unbound and decay almost instantly through emission of protons or via fast beta decay to nearby, more stable species.

If Sn-72 were produced in a high-energy reaction, its lifetime would be extremely short, on the order of nanoseconds or less, and it would be detected only through indirect observation of its decay products. Possible decay channels would depend on the relative energies of the competing processes, but proton emission and beta-plus decay to neighboring isotopes (such as In-72 or Sb-72) are anticipated for highly proton-rich systems.

Presently, there is no experimental confirmation of Sn-72. It remains a theoretical point of reference in studies of the proton-rich edge of the tin isotopic chain and in tests of nuclear models that describe binding energies, shell effects, and drip-line behavior in light to medium-mass nuclei.

See also: Tin isotopes, Proton drip line, Nuclear binding energy.