Sm-146 production by the gamma-process

Following the recent confirmation of the correlation of the ratio Nd-142/Nd-144 with the Sm/Nd ratio in some meteorites (reported by Prinzhofer, Papanastassiou, and Wasserburg in 1989), we have reexamined the production of Sm-146, a Nd-142 progenitor, by the gamma-process in supernovae. Reasonable changes in nuclear reaction rates for the photodestruction. of Gd-148, especially its destruction by Gd-148(gamma, n)Gd-147 and Gd-148(gamma, alpha)Sm-144, now yield a Sm-146 production increased by up to 20 times that of our previous work. The increased value is consistent with the cosmochemical data. A laboratory measurement of the cross section for Sm-144(alpha, gamma)Gd-148 at a center of mass energy near 10 MeV is feasible and would greatly clarify an uncertain situation for nucleosynthesis and cosmochronology.