Photodisintegration cross section measurements on 186W, 187Re, and 188Os:: Implications for the Re-Os cosmochronology -: art. no. 025808

Cross sections of the W-186, Re-187, Os-188(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-sigma for the neutron capture on the 9.75 keV state in Os-187. Implications of F-sigma for the Re-Os cosmochronology are discussed with a focus on the uncertainty in the estimate of the age of the galaxy.