Cosmochronology with the87Rb/87Sr isobaric pair

The long-lived cosmochronometer⁸⁷Rb (T _1/2=4.8×10¹⁰ yr) is studied. As its origin is partly due tos- and partly tor-process nucleosynthesis it can provide information about the time histories of these processes. The methods of using⁸⁷Rb quantitatively for a chronological analysis are described. Tentative calculations based on existing experimental data are also presented. The data indicate a larger-process age than thes-process age.