DREB 2012 - Direct Reactions with Exotic Beams

Fusion reactions and neutron transfer in collisions induced by Li isotopes on Sn targets

29 Mar 2012, 15:25

20m

Aula Magna, Faculty of SMFN

Talk Session 13

Speaker

Maria Fisichella (Università di Messina / LNS-INFN)

Description

Recently experimental evidences have been observed concerning the enhancement of the sub-barrier fusion cross section due to neutron transfer, both in reaction with stable nuclei [1,2] and with weakly bound nuclei [3]. The enhancement seems to be related to the sign of the Q-value for neutron transfer. A new mechanism has been proposed [4] for the sub-barrier fusion of weakly bound nuclei, in which an intermediate rearrangement of valence neutrons with positive Q-value may lead to a gain in kinetic energy of the colliding nuclei and, thus, to enhancement of the barrier penetrability and therefore of the fusion cross-section. To investigate the role played by the coupling to transfer channels having positive Q-value, we proposed to study the fusion of lithium isotopes with a combination of different Sn isotopes:6Li+120Sn,7Li+119Sn,8Li+118Sn and 9Li+117Sn. All these reactions lead to the same compound nucleus but are characterized by different Q-value for neutron transfer.The fusion cross section are measured by using an activation technique where the radioactive evaporation residues are identified by the X-ray emission following their electron capture decay.In this contribution, results of the 6Li+120Sn, 7Li+119Sn which have been recently measured at LNS(Catania)will be discussed. [1]Trotta et al,Phys.Rev.C65,011601(2002) [2] Stefanini et al,Phys.Rev.C74,034606 (2006) [3] Penionzhkevich et al,Phys.Rev.Lett.96,162701(2006) [4] Zagrebaev et al., Phys.Rev.C 67 061601(R) (2003)

Presentation materials

Slides

fisichella_dreb2012.pdf