Fission fragments of actinide and superheavy nuclides in primordial material of the Solar system and the problem of their origin

Abstract

Results of an estimation of the possible contribution of fission products into the abundance of atomic masses for transiron elements and xenon isotopes in different objects of the Solar system are presented in the work. A recent systematization of the mass distribution of fission fragments for actinide nuclides and compound nuclei of superheavy elements at low excitation energies has allowed to reveal the humps on the mass distribution curves of Solar system matter that are analogous to the mass fragment distributions at asymmetric fission for nuclei of thorium and uranium, and superheavy elements (Z ≈ 114 and 126). These results are in accordance with the ratios of heavy xenon isotopes, found out in products of fragmental fission. Two basic sources of fission fragments in transiron area are revealed for matter of the Solar system. The first of them, connected with the fission of superheavy progenitors and characterized by Dy, Pt and Te enrichment (A = 164, 195 and 130), is typical for carbonaceous chondrites and the Solar photosphere. The second one, connected with Th and U fission and having the maxima of Sr, Zr and Ba abundances (A = 88, 94 and 138) is observed in the crusts of the Earth and the Moon. In the suggested scenario the basic phase of r-process occurred after a synthesis of actinide and superheavy nuclides and was the reason of local modifications in the humps of their fission fragments distributions which coincide with the "waiting points" of r -process.