Atomic nuclei decay modes by spontaneous emission of heavy ions

The great majority of the known nuclides with Z>40, including the so-called stable nuclides, are metastable with respect to several modes of spontaneous superasymmetric splitting. A model extended from the fission theory of alpha decay allows one to estimate the lifetimes and the branching ratios relative to the alpha decay for these natural radioactivities. From a huge amount of systematic calculations it is concluded that the process should proceed with maximum intensity in the trans-lead nuclei, where the minimum lifetime is obtained from parent-emitted heavy ion combinations leading to a magic ${(}^{208}$Pb) or almost magic daughter nucleus. More than 140 nuclides with atomic number smaller than 25 are possible candidates to be emitted from heavy nuclei, with half-lives in the range of ${10}^{10}$–${10}^{30}$ s: ${}_{}{}^5{}_{}{}^{}\mathrm{He}$, ${}_{}{}^{8–10}{}_{}{}^{}\mathrm{Be}$, ${}_{}{}^{11}{}_{}{}^{}$,12B, ${}_{}{}^{12–16}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{13–17}{}_{}{}^{}\mathrm{N}$, ${}_{}{}^{15–22}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{18–23}{}_{}{}^{}\mathrm{F}$, ${}_{}{}^{20–26}{}_{}{}^{}\mathrm{Ne}$, ${}_{}{}^{23–28}{}_{}{}^{}\mathrm{Na}$, ${}_{}{}^{23–30}{}_{}{}^{}\mathrm{Mg}$, ${}_{}{}^{27–32}{}_{}{}^{}\mathrm{Al}$, ${}_{}{}^{28–36}{}_{}{}^{}\mathrm{Si}$, ${}_{}{}^{31–39}{}_{}{}^{}\mathrm{P}$, ${}_{}{}^{32–42}{}_{}{}^{}\mathrm{S}$, ${}_{}{}^{35–45}{}_{}{}^{}\mathrm{Cl}$, ${}_{}{}^{37–47}{}_{}{}^{}\mathrm{Ar}$, ${}_{}{}^{40–49}{}_{}{}^{}$ K, ${}_{}{}^{42\mathrm{-}51...}{}_{}{}^{}\mathrm{Ca}$, ${}_{}{}^{44–53}{}_{}{}^{}$ Sc, ${}_{}{}^{46–53}{}_{}{}^{}\mathrm{Ti}$, ${}_{}{}^{48–54}{}_{}{}^{}\mathrm{V}$, and ${}_{}{}^{49–55}{}_{}{}^{}$ Cr. The shell structure and the pairing effects are clearly manifested in these new decay modes.