We have determined lead ( Pb ) abundances for twelve red giants having [ Fe/H ] between -2.1 and -1.3 , and its upper-limits for two lower metallicity objects , as well as the abundances of lanthanum ( La ) and europium ( Eu ) .
The averages of [ Pb/Fe ] and [ Pb/Eu ] are -0.3 and -0.6 , respectively , and no clear increase of these ratios with increasing metallicity is found .
The [ La/Eu ] values are only slightly higher than that of the r-process component in solar-system material .
Combining the previous studies for globular clusters , these results suggest little contribution of the s-process to Pb of the field stars studied here , supporting the estimate of Pb production by the r-process from the solar-system abundances .