The nucleosynthesis of heavy neutron-deficient nuclei in a stellar photon bath at the temperatures relevant for the astrophysical $\gamma$ process was investigated. In order to derive $(\gamma ,n)$ cross sections and reaction rates, the stellar photon bath was simulated by the superposition of several bremsstrahlung spectra with different end-point energies. As a first test for this method, the $(\gamma ,n)$ reaction rates of the platinum isotopes ${}^{190}\mathrm{Pt},$ ${}^{192}\mathrm{Pt},$ and ${}^{198}\mathrm{Pt}$ were derived. The results are compared to other experimental data and theoretical calculations.

• Received 29 September 2000

DOI:https://doi.org/10.1103/PhysRevC.63.055802