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 (²⁰⁸Pb) 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 10¹⁰--10³⁰ s: ⁵He, ⁸⁻⁻¹⁰Be, ¹¹,12B, ¹²⁻⁻¹⁶C, ¹³⁻⁻¹⁷N, ¹⁵⁻⁻²²O, ¹⁸⁻⁻²³F, ²⁰⁻⁻²⁶Ne, ²³⁻⁻²⁸Na, ²³⁻⁻³⁰Mg, ²⁷⁻⁻³²Al, ²⁸⁻⁻³⁶Si, ³¹⁻⁻³⁹P, ³²⁻⁻⁴²S, ³⁵⁻⁻⁴⁵Cl, ³⁷⁻⁻⁴⁷Ar, ⁴⁰⁻⁻⁴⁹ K, ^42-51.0ex0ex.0ex0ex.Ca, ⁴⁴⁻⁻⁵³ Sc, ⁴⁶⁻⁻⁵³Ti, ⁴⁸⁻⁻⁵⁴V, and ⁴⁹⁻⁻⁵⁵ Cr. The shell structure and the pairing effects are clearly manifested in these new decay modes.