Research of high energy collective states at high excitation energy in nuclei N. Alamanos, J. Arvieux, B. Berthier, B. Bonin, G. Bruge, M. Buenerd, J. Dechargé, H. Faraggi, D. Gogny, Y. Terrien 1982

Collective excitation modes in nuclei

GDR : a well known giant resonance

GQR : another well known giant resonance

Special interest for monopole modes, because they give access to the compressibility of nuclear matter RPA calculations predict the existence of collective high energy modes in nuclei

Transition densities BoninGogny-DechargéSatchler Macro RPA Macro

Experiment : (alpha, alpha’) inelastic scattering on 208 Pb, 116 Sn, 58 Ni; E alpha = 430, 480 MeV

Detection

One excitation spectrum…

…Many excitation spectra Note the ripples of the angular distribution of the cross section

Multipole decomposition Calculation : Transition densities (RPA)  transition potentials  Coupled channel calculation (ECIS, N. Alamanos, J. Raynal)  angular distribution of cross section  multipolarity of the excited states can be deduced from the oscillations of the cross section

Same response function extracted for E= 340 and 480 MeV

Agreement of experiment with RPA calculations

Conclusions High multipolarity giant resonances predicted by RPA calculations have been found. The nucleus still behaves collectively even at high excitation energy!

Epilogue Collaboration Saclay-B3 (J. Dechargé) continued with the search of other resonances with polarized deuterons (PhD Th. Mandon).