Enhanced Sensitivity to the Iso-Vector Giant Quadrupole Resonance using Linearly Polarized $\gamma$-ray Beams at HI$\gamma$S

Data have been collected at the High Intensity $\gamma$-ray Source (HI$\gamma$S) to investigate the Isovector Giant Quadrupole (IVGQR) Resonance region in $^{209}$Bi, $E_{\gamma}=11-30$ MeV. Linearly polarized $\vec{\gamma}$-rays were incident upon an isotopically pure ($>$99.9\%) $^{209}$Bi target. Angular distributions of the scattered $\gamma$-rays both parallel and perpendicular to the plane of polarization were detected using the HI$\gamma$S NaI Detector Array (HINDA). An enhancement in sensitivity to the IVGQR parameters is observed in the angular distribution of the polarization ratio of scattered $\gamma$-rays. During the 80 hour run, the nearly mono-energetic $\vec{\gamma}$-ray intensities were $1-5\times10^{7}\gamma$'s/sec on target and statistical accuracies of 1-3\% were achieved. Angular distributions of the polarization ratios and subsequent extraction of the IVGQR resonance parameters for the $^{209}$Bi nucleus will be reported.