Continuumγrays feeding normal and superdeformed states in Gd nuclei

Abstract

The feeding mechanism of the superdeformed bands in ${}^{147}$Gd and ${}^{148}$Gd has been studied via the ${}^{124}$Sn + ${}^{29}$Si reaction at a beam energy of 157 MeV. Using the BGO inner ball of the GASP array, high-energy $\ensuremath{\gamma}$ rays have been detected in coincidence with discrete transitions deexciting normal-deformed (ND) and superdeformed (SD) states in the final product nuclei. The slope of the measured high-energy $\ensuremath{\gamma}$-ray spectra depends strongly on the number of emitted neutrons and is somewhat lower for spectra in coincidence with SD bands than for those in coincidence with ND structures. Both observations are qualitatively reproduced by statistical model Monte Carlo calculations, which point out the importance of angular momentum effects in the emission of energetic $\ensuremath{\gamma}$ rays. The present data exclude the enhanced population of SD bands when fed through high-energy $E1$ transitions.