Photon strength functions from photon scattering

We present photon-scattering experiments using bremsstrahlung at the $\gamma $ELBE facility of Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and using quasi-monoenergetic, polarized $\gamma $ rays at the HI$\gamma $S facility of the Triangle Universities Nuclear Laboratory (TUNL) in Durham. In the analysis of the spectra measured by using bremsstrahlung at $\gamma $ELBE, we include intensity in the quasi-continuum and perform simulations of statistical $\gamma $-ray cascades using the code $\gamma $DEX to estimate intensities of inelastic transitions to low-lying excited states. Simulated average branching ratios are compared with model-independent branching ratios obtained from spectra measured by using monoenergetic $\gamma $ beams at HI$\gamma $S. Photoabsorption cross sections deduced in this way are presented for selected nuclides. Strength in the energy region of the so-called pygmy dipole resonance (PDR) is considered in nuclei around mass 80 and in xenon isotopes.\\[4pt] In collaboration with Ralph Massarczyk, Los Alamos National Laboratory.