The s ‐Process Branching at 185 W

Abstract

The neutron capture cross section of the unstable nucleus 185 W has been derived from experimental photo-activation data of the inverse reaction 186 W(, n) 185 W. The new result of ¼ 687 AE 110 mbarn confirms the theoretically predicted neutron capture cross section of 185 W of % 700 mbarn at kT ¼ 30 keV. A neutron density in the classical s-process of n n ¼ 3:8 þ1:1 À0:9 À Á Â 10 8 cm À3 is derived from the new data for the 185 W branching. In a stellar s-process model, one finds a significant overproduction of the residual s-only nucleus 186 Os.