W. von Oertzen — Page 2

arXiv2001

Enhanced excitation of Giant Pairing Vibrations in heavy-ion reactions induced by weakly-bound projectiles

The use of radioactive ion beams is shown to offer the possibility to study collective pairing states at high excitation energy, which are not usually accessible with stable projectiles because of large energy mismatch. In the case of two-neutron stripping reactions induced by 6He, we predict a population of the Giant Pairing Vibration in 208Pb or 116Sn with cross sections of the order of a millibarn, dominating over the mismatched transition to the ground state.

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arXiv2001

The population of deformed bands in $^{48}$Cr by emission of $^{8}$Be from the $^{32}$S + $^{24}$Mg reaction

Using particle-$γ$ coincidences we have studied the population of final states after the emission of 2 $α$-particles and of $^{8}$Be in nuclei formed in $^{32}$S+$^{24}$Mg reactions at an energy of $\textrm{E}_{\rm L}(^{32}\textrm{S}) = 130 {\rm MeV}$. The data were obtained in a setup consisting of the GASP $γ$-ray detection array and the multidetector array ISIS. Particle identification is obtained from the $Δ$E and E signals of the ISIS silicon detector telescopes, the $^{8}$Be being identified by the instantaneous pile up of the $Δ$E and E pulses. $γ$-ray decays of the $^{48}$Cr nucleus are identified with coincidences set on 2 $α$-particles and on $^{8}$Be. Some transitions of the side-band with $K^π=4^{-}$ show stronger population for $^{8}$Be emission relative to that of 2 $α$-particles (by a factor $1.5-1.8$). This observation is interpreted as due to an enhanced emission of $^{8}$Be into a more deformed nucleus. Calculations based on the extended Hauser-Feshbach compound decay formalism confirm this observation quantitatively.

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