Study of fossil tracks due to 50≤Z≤92 Galactic cosmic ray nuclei in extraterrestrial crystals — Results and perspectives

Abstract

The new approach to the problem of investigation of charge and energy spectra of ultra heavy Galactic cosmic ray nuclei, based on a fossil track study of extraterrestrial olivine crystals was proposed. The results of an investigation of ultra heavy Galactic cosmic ray nuclei (50≤Z≤92) in meteoritic olivine crystals are presented. The technique was based on calibration to these crystals with acccelerated Xe, Au, Pb and U ions and partial annealing of “fresh” and “fossil” tracks. It allows us to get first the charge spectra of Galactic cosmic ray nuclei based on fossil track length study in meteoritic and Moon crystals. The comparative studies of the spectra of “fossil” tracks and tracks due to 208Pb and 238U nuclei have shown that the group of 210 μm “fossil” tracks observed in 1980 at LNR, JINR is due to TH-U nuclei — products of recent r-process nucleosynthesis in our Galaxy. The method in principle allows one to resolve PtPb peaks in fossil tracks, to establish the upper limit of the abundances of Z>110 nuclei in the Galactic cosmic rays at the level ≤10 −3 to the abundance of actinide nuclei and to get information about the history of Z>50 cosmic rays in the time interval up to 220 M.A.