Decay of 1, 2 and 3-Phonon States in 40Ca

Inelastic scattering of Ca-40 on Ca-40 at 50 A.MeV has been measured in coincidence with protons at the GANIL facility using a very performant set-up. The SPEC spectrometer was associated with 240 CsI(TI) scintillators of the INDRA 4 pi array, allowing for the measurement of complete decay events. The missing energy method was applied to these events to study the particle decay of collective states. 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 giant resonance state. A significant direct decay branch by alpha-particles of the GQR is also measured for the first time.