Projectile breakup dynamics for 6Li + 59Co : Kinematical analysis of $ \alpha$ - d coincidences

Abstract

A study of the kinematics of the α-d coincidences in the 6 Li + 59 Co system at a bombarding energy of E lab = 29.6 MeV is presented. With exclusive measurements performed over different angular intervals it is possible to identify the respective contributions of the sequential and direct projectile breakup components. The angular distributions of both breakup components are fairly well described by the Continuum-Discretized Coupled-Channels framework (CDCC). Furthermore, a careful analysis of these processes using a semiclassical approach provides information on both their lifetime and their distance of occurrence with respect to the target. Breakup to the low-lying (near-threshold) continuum is delayed, and happens at large internuclear distances. This suggests that the influence of the projectile breakup on the complete fusion process can be related essentially to direct breakup to the 6 Li high-lying continuum spectrum.PACS. 25.70.Mn Projectile and target fragmentation

Coupled-Channel Effects in Collisions Between Heavy Ions Near the Coulomb Barrier

“…2. Thess results are consistent with rather low breakup cross sections measured for the 6,7 Li+ 59 Co reactions even at incident energies larger than the Coulomb barrier [39,40,41]. But the coupling of the breakup channel is extremely important for the CDCC analysis of the angular distributions of the elastic scattering [47] as shown in Fig.…”

“…For this reaction it was not necessary to use a sophisticated four-body CDCC framework. The CDCC cross sections [47] are in agreement with the experimental ones [16,40,41], both in shapes and magnitudes within the uncertainties. The relative contributions of the 6 Li SBU and DBU to the incomplete fusion/transfer process has been discussed in great details in Refs.…”

“…For reactions induced by weakly bound nuclei [16,17,25,26,27,28,39,40,41] and exotic nuclei [18,19,20,21,22,38,42,43,44,45,46], the breakup channel is open and plays a key role in the fusion process near the Coulomb barrier similarly to the transfer-channel coupling described in the previous section. It is therefore appropriate to use the Continuum-Discretized Coupled-Channel (CDCC) approach [47,48,49,50] to describe the influence of the breakup channel in both the elastic scattering and the fusion process at sub-barrier energies.…”

“…A more detailed investigation of the breakup process in the 6 Li+ 59 Co reaction with particle coincidence techniques is now proposed to discuss the interplay of fusion and breakup processes. Coincidence data compared to three-body kinematics calculations reveal a way how to disentangle the contributions of breakup, incomplete fusion and/or transfer-reemission processes [39,40,41]. Fig.…”

“…[39,40,41] by considering the corresponding lifetimes obtained by using a semi-classical approach fully described in a previous publication [39]. We con- clude that the flux diverted from complete fusion to incomplete fusion would arise essentially from DBU processes via high-lying continuum (non-resonant) states of 6 Li; this is due to the fact that both the SBU mechanism and the low-lying DBU processes from low-lying resonant 6 Li states occur at large internuclear distances [39,40,41]. Work is in progress to study incomplete fusion for 6 Li+ 59 Co within a newly developed 3-dimensional classical trajectory model [51].…”