Compton Scattering on $^{209}Bi$ at HI$\gamma$S From $E_{\gamma}=11-30$ MeV
ORAL
Abstract
New data collected at the High Intensity $\gamma$-ray Source (HI$\gamma$S) were taken to investigate the Iso-Vector Giant Dipole (IVGDR) and Giant Quadrupole (IVGQR) Resonance Regions in $^{209}$Bi, $E_{\gamma}=11-30$ MeV. Linearly polarized $\vec{\gamma}$-rays were incident upon an isotopically pure ($>$99.9\%) $^{209}$Bi target and the scattered $\gamma$-rays were detected using the HI$\gamma$S NaI Detector Array (HINDA). HINDA is an array of large (10''x10'') core detectors surrounded by 3'' thick NaI shields that are segmented optically into 8 individual segments. This assembly was run in an anti-coincidence mode to reduce background and improve the resolution as well as a coincidence mode to isolate the first escape peak. During the 150 hour run, the nearly mono-energetic $\vec{\gamma}$-ray intensities were $1\times10^{5}-1\times10^{7}\gamma$'s/sec on target and statistical accuracies of 1-3\% were achieved. Preliminary analysis of angular distributions of cross sections and analyzing powers as well as absolute cross sections will be reported.
*Supported by US DOE Grant Nos. DE-FG02-97ER41033, DE-FG02-03ER41231 and NSF Grant No. PHY-0619183.
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