First Measurement of the Giant Monopole and Quadrupole Resonances in a Short-Lived Nucleus: Ni 56

The isoscalar giant monopole resonance (GMR) and giant quadrupole resonance (GQR) have been measured in the $^{56}\mathrm{Ni}$ unstable nucleus by inducing the $^{56}\mathrm{Ni}(d,{d}^{\ensuremath{'}})$ reaction at $50A\text{ }\text{ }\mathrm{MeV}$ in the Maya active target at the GANIL facility. The GMR and GQR centroids are measured at $19.3\ifmmode\pm\else\textpm\fi{}0.5\text{ }\text{ }\mathrm{MeV}$ and $16.2\ifmmode\pm\else\textpm\fi{}0.5\text{ }\text{ }\mathrm{MeV}$, respectively. The corresponding angular distributions are extracted from 3\ifmmode^\circ\else\textdegree\fi{} to 7\ifmmode^\circ\else\textdegree\fi{}. A multipole decomposition analysis using distorted wave Born approximation with random phase approximation transition densities shows that both the GMR and the GQR exhaust a large fraction of the energy-weighted sum rule. The demonstration of this new method opens a broad range of giant resonance studies at intermediate-energy radioactive beam facilities.