Evidence For A Three-Phonon Giant Resonance State In Ca-40 Nuclei

Inelastic scattering of Ca-40 on Ca-40 at 50 MeV/A has been measured in coincidence with protons at the GANIL facility. The SPEG spectrometer was associated with 240 CsI(Tl) scintillators of the INDRA 4 pi array, allowing for the measurement of complete decay events. The missing energy method was applied to these events. For events with excitation energy between 42 and 55 MeV, a direct decay branch by three protons towards the low energy states of Cl-37 gives the first evidence for a 3-phonon state built with giant resonances.