Probing the Pygmy Dipole Resonance in $^{112}$Sn and $^{124}$Sn

A high-resolution nuclear fluorescence experiment of enriched $^{112,124}$Sn has been performed using the 100\% polarized photon beam at the High-Intesity Gamma-Ray Source (HI$\gamma$S). Four HPGe detectors were used to observe 66 dipole transitions with excitation energies between 6.4 MeV and 8.4 MeV. The parity of each of the 21 previously identified transitions in $^{124}$Sn was found to be J$^{\pi}$=1$^{-}$. In addition, 10 new levels in $^{124}$Sn were identified, as well as 5 new levels in $^{112}$Sn all of which are E1 excitations with the exception of a 6.917 MeV state in $^{124}$Sn excited by an M1 transition. Both nuclei exhibited considerable decay strength to the first excited state. We shall discuss the possible causes of these decays as well as their implications to r-process nucleosynthesis. The measurements will be compared with calculations using quasiparticle random-phase approximations.