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

The isoscalar giant monopole resonance (GMR) and giant quadrupole resonance (GQR) have been measured in the ⁵⁶Ni unstable nucleus by inducing the ⁵⁶Ni(d,d^′) reaction at 50A  MeV in the Maya active target at the GANIL facility. The GMR and GQR centroids are measured at 19.3±0.5  MeV and 16.2±0.5  MeV, respectively. The corresponding angular distributions are extracted from 3° to 7°. 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.