Near barrier fusion excitation function ofLi6+Pb208

Abstract

The fusion cross sections of 6 Li+ 208 Pb system at energies near the barrier have been measured by means of the evaporation residue method and have been calculated in terms of the coupled-channels model, taking into account single and double phonon octupole excitations of 208 Pb and the 3 + rotational state of 6 Li. By comparing the experimental results with the theoretical calculations and with the fusion cross section of 16 O+ 208 Pb, in which no breakup happens, we conclude that the fusion cross sections of 6 Li+ 208 Pb are suppressed at abovebarrier energies due to the effects of 6 Li breakup, but below the barrier, the effects of breakup are not clear.

Suppression of complete fusion due to breakup in the reactionsB10,11+Bi209

“…The latter correspond to the incomplete fusion reactions associated with the most favorable breakup channels. It is clear from the large reduction in P f is as the captured mass decreases that the contribution of fission following ICF of 6,7 Li or 4 He will be negligible compared with that resulting from CF. As an example, we can estimate the maximum contribution to the fission yield from ICF for the 10 B + 209 Bi reaction.…”

“…Studies with weakly bound light stable nuclei indicate that complete fusion (CF) cross sections (defined experimentally [2,3] as absorption of all the charge of projectile) are suppressed at above-barrier energies in comparison with the predictions of both the single barrier penetration model (SBPM) and the coupled-channels (CC) model [2,3,4,5,6,7]. This is attributed to the low binding energy of the projectiles, which can break up prior to reaching the fusion barrier.…”

Extended optical model analyses of elastic scattering and fusion cross sections for theLi6+Pb208system at near-Coulom

“…We take σ exp F from Ref. [13], but since the . For these preliminary analyses, we assume the optical potential to be a sum of V 0 (r) + iW I (r) and…”

“…, σ exp F ) by taking dσ exp E /dΩ, and σ exp F from the literature [2,13]. In calculating the χ 2 value, we simply assumed 1% errors for all the experimental data.…”

“…In order to test this idea, we have thus carried out [8,9] simultaneous χ 2 analyses of elastic scattering and fusion cross section data for the 6 He+ 209 Bi [10,11,12], 6 Li+ 208 Pb [2,13,14], and 9 Be+ 209 Bi [15,16] systems at near-Coulomb-barrier energies in the framework of the extended optical model [17,18,19] that introduces two types of complex polarization potentials, the DR and fusion potentials. In such analyses, in addition to the elastic scattering cross sections dσ exp E /dΩ, the measured fusion cross section σ exp F , was taken into account together with the total experimental DR cross section, σ exp D , if available, or the semi-experimental DR cross section, σ semi−exp D , if σ exp D was not available.…”