Photoactivation Of Ta-180(M): Does It Affect S-Process Nucleosynthesis Of Nature'S Rarest Stable Isotope?

The depopulation of the quasistable isomer (J(pi) = 9(-), E-x = 75 keV) in Ta-180 through resonant photoabsorption was studied with intense bremsstrahlung. The results show evidence for a deexciting level with an energy of 1.085 MeV or below, leading to a dramatic acceleration of the isomer decay to the short-lived J(pi) = 1(+) ground state under stellar s-process conditions. Consequences for a possible nucleosynthesis of nature's rarest isotope Ta-180 within the s process are discussed.