Dynamical Dipole mode in the40,48Ca +152,144Sm fusion reactions at 11 MeV/nucleon

C Parascandolo,F Soramel,C Agodi,R Alba,E De Filippo,D Pierroutsakou,V Baran,F Farinon,D Torresi,M Mazzocco,R Coniglione,A Boiano,A Del Zoppo,U Emanuele,M Di Toro,E Strano,M La Commara,C Mazzocchi,C Signorini,M Trimarchi,C Maiolino,B Martin,A Guglielmetti,M Romoli,D Santonocito,M Colonna,Carmelo J Rizzo ,Riccardo Silvestri ,A Trifirò

doi:10.1051/epjconf/201611708016

Abstract

The excitation of the dynamical dipole mode along the fusion path was investigated in the formation of a heavy compound nucleus in the A=190 mass region. To form the compound nucleus, the 40 Ca + 152 Sm and 48 Ca + 144 Sm reactions were employed at Elab =11 and 10.1 MeV/nucleon, respectively. Both fusion–evaporation and fission events were studied simultaneously for the first time. Our results for evaporation and fission events (preliminary) show that the dynamical dipole mode survives in reactions involving heavier nuclei than those studied previously.

Highlights

The existence of the DD mode has been probed in deep inelastic and fusion-evaporation heavy-ion collisions [5,6,7,8,9]
The average excitation energy, the average mass and the average charge of the composite system after pre-equilibrium particle emission were evaluated by studying the energy spectra of the light charged particles (p, α) in coincidence with evaporation residues, while the pre-equilibrium neutron emission was estimated from our proton data and from systematics
These spectra were analyzed with a moving source fit where the particles were assumed to be emitted isotropically from two moving sources: a slow source simulating the statistical evaporation from the hot CN and an intermediatevelocity source related to the pre-equilibrium particles emitted by the composite system before thermalization

Summary

Introduction

The existence of the DD mode has been probed in deep inelastic and fusion-evaporation heavy-ion collisions [5,6,7,8,9]. The fission events were selected by detecting the two kinematically coincident fission fragments with position sensitive PPACs, centered at θ = 52.5◦ symmetrically around the beam axis at 16 cm from the target covering 22◦ in both θ and φ and allowing the study of γ-ray - fragment angular correlations.

Results

Conclusion