On search and identification of tracks due to short-lived SHE nuclei in extraterrestrial crystals

The unique approach for search and unambiguous identification of short-lived (T1/2=103-107 years) superheavy nuclei in cosmic-ray products of the recent nucleosynthesis in our Galaxy are discussed. It is based on: (a) the ability of non-conducting crystals to register and to store for many million years the tracks due to fast nuclei with atomic number Z≥20 ('fossil' tracks); (b) calibrations of the said crystals with accelerated heavy ions (20≤Z≤92) and on revealing the volume etchable track length (VETL) of the fast nuclei coming to rest inside crystals--both of fossil and 'fresh' tracks--to determine the charge distribution of cosmic-ray nuclei tracks and (c) the so-called 'four-zone' model of tracks in crystals (and also glasses) which provides not only the VETL track length dependence for 20≤Z≤92 nuclei but also demonstrates the regular annealing behavior of VETL of 20≤Z≤92 nuclei in a broad temperature interval. This approach was first applied in the early 1980s to investigate the 'fossil' tracks due to 22≤Z≤92 cosmic-ray nuclei in olivine crystals from meteorites-pallasite Marjalahti and Eagle Station. The discovery of Th-U cosmic-ray nuclei tracks in 1980 was unambiguously confirmed by calibrations of the same crystals with 238U, 197Au and 208Pb accelerated ions in the late 1980s. More than 1600 tracks due to cosmic-ray actinide nuclei were measured during the last two decades of the 20th century. Also, 11 anomalously long tracks (track length exceeds by a factor (1.6±0.1) the track length due to Th-U nuclei were measured. The detailed analysis shows that at least 5 of these tracks could not be attributed to the Th-U nuclei. It means that now we have a preliminary proof on the existence Z≥110 nuclei in cosmic-rays. The abundance is Z≥110/Th-U=(1-3)x10-3 in Z≥110 freshly formed cosmic-rays (time interval 103-107 years). The method proposed can provide the necessary and sufficient conditions for the discovery of Z≥110 nuclei in nature