Measurements of Dipole Excitations in $^{48}$Ca Between E$_{\gamma}$ = 9.5 and 15.3 MeV
ORAL
Abstract
$^{48}$Ca photodisintegration cross sections were measured using $\gamma$-ray beams of 34 different energies between 9.5 and 15.3 MeV generated with the TUNL High-Intensity $\gamma$-ray Source (HI$\gamma$S). The cross sections were measured with a 2.7 g $^{48}$Ca target enriched to 92\% using an array of $^{3}$He proportional-counters embedded in thermalizing polyethylene. The absolute cross sections for the $^{48}$Ca($\gamma$,n) reaction were obtained by normalization to the well known $^{2}$H($\gamma$,n) reaction cross sections. Single neutron emission is the dominant channel in this energy range and its detection provides a measurement of dipole excitation strength such as the previously identified M1 strength at E$_{\gamma}$ = 10.22 MeV,\footnote{W.Steffen \textit{et al.} Nucl. Phys. A \textbf{404}, 413 (1983).} for which a new value will be presented. Structures on the low-energy tail of the E1 GDR were also observed and will be presented.
*This work was supported in part by USDOE Grant Nos. DE-FG02-97ER41041, DE-FG02-03ER41231, DE-FG02-87ER-40316, and DHS Grant No. 2008-DN-077-ARI010-0.
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