Photodisintegration cross section measurements on {sup 186}W, {sup 187}Re, and {sup 188}Os: Implications for the Re-Os cosmochronology

Cross sections of the {sup 186}W, {sup 187}Re, {sup 188}Os({gamma},n) reactions were measured using quasimonochromatic photon beams from laser Compton scattering with average energies from 7.3 to 10.9 MeV. The results are compared with the predictions of Hauser-Feshbach statistical calculations using four different sets of input parameters. In addition, the inverse neutron capture cross sections were evaluated by constraining the model parameters, especially the E1 strength function, on the basis of the experimental data. The present experiment helps to further constrain the correction factor F{sub {sigma}} for the neutron capture on the 9.75 keV state in {sup 187}Os. Implications of F{sub {sigma}} for the Re-Os cosmochronology are discussed with a focus on the uncertainty in the estimate of the age of the galaxy.