Abundance of actinides in cosmic radiation

Abstract

Ultra heavy (UH) cosmic rays of Z⩾65 are produced either by s- or r-process of nucleosynthesis. Since these two processes occur under different astrophysical environments, the relative abundances of UH ions could be an important parameter in finding their source and origin. Data analysis is carried out on four detector stacks exposed in space by UH cosmic ray experiment on board LDEF. Scanning and analysis of ∼0.21 m 2 detector area resulted in finding of 72 UH ions (68⩽ Z⩽96) including two actinides (88⩽ Z⩽100). The ratio of actinides to that of sub-actinides is found to be ∼0.034±0.024, which is well within the observational limits of other experiments. Results suggest possible sources, which predominantly ejects r-process synthesized material.