Partial photoneutron cross sections for the isomeric state 180Tam.

Photoneutron cross sections for {sup 181}Ta({gamma},n){sup 180}Ta{sup m} were determined from simultaneous measurements of total cross sections ({sigma}{sup tot}) and ground-state cross sections ({sigma}{sup gs}) for {sup 180}Ta in photodisintegration of {sup 181}Ta with laser Compton-backscattered {gamma} rays. Techniques of direct neutron counting and photoactivation were used for the measurement of {sigma}{sup tot} and {sigma}{sup gs}, respectively. The partial cross sections for the isomeric state serves as a novel probe of the nuclear level density of {sup 180}Ta. Implications for the p- and s-process nucleosynthesis of {sup 180}Ta{sup m} are given.