Multiphonon states built with giant resonances Original Research Article

The two-phonon states built with giant resonances have been observed through a large variety of experiments. A new experiment studying the inelastic scattering of40Ca on40Ca at 50 A.MeV has been measured at GANIL by detecting scattered40Ca in coincidence with light charged particles. For the first time, the SPEG spectrometer was associated to 240 CsI(Tl) scintillators of the INDRA 4π array. The direct decay method, successfully used in previous experiments to sign the presence of multiphonon states, is applied to the excitation energy region of the GQR, the double and the triple GQR. The previous results concerning the GQR and the 2-phonon state built with the GQR are confirmed. Evidence is given for the excitation of a 3-phonon state, characterized by its 3 proton direct decay branch and indication are given for a four-phonon state.