Smoothing of structure in the fusion and quasielastic barrier distributions for the20Ne+

Abstract

We present simultaneously measured barrier distributions for the 20 Ne + 208 Pb system derived from largeangle quasielastic scattering and fusion, in the latter case by means of the detection of fission fragments. Both distributions turned out to be smooth, in spectacular disagreement with the results of standard coupled-channels calculations. Namely, they do not posses the strong structure expected from coupled-channels calculations, even if apparently they take into account explicitly all relevant strong couplings. This points to the importance of weak channels, i.e., transfer reactions and scattering connected with noncollective excitations.

Fusion and quasi-elastic scattering in theLi6,7+Au197Palshetkar1, Thakur2, Nanal3 et al. 2014Phys. Rev. C640220View full textAdd to dashboardCite

“…[38], taking into account experimental values of the fusion cross section and height, radius, and curvature of the barrier. Figure 7 shows a systematic comparison of the present data with 6,8 He on 197 Au from Refs. [4] and [18].…”

“…In the case of reactions with neutron-rich radioactive ion beams, the coupling to transfer is also found to be important [2]. Recent results in the 8 He + 197 Au reaction indicate that the sub-barrier total reaction cross section is dominated by direct reactions, in the form of one-and two-neutron stripping [4]. In the case of weakly bound stable nuclei, it has been observed that CF cross sections at above-barrier energies are suppressed compared to calculations which do not include the effect of breakup coupling [1,2].…”

“…The incoming flux that penetrates the barrier corresponds to the transmission (T) through the barrier, while the flux scattering from the barrier corresponds to the reflection (R) at the barrier. Owing to conservation of the reaction flux, the fusion and QEL scattering process can be considered complementary and barrier distributions obtained from both types of measurements are expected to be similar [8]. Recently such studies have been carried out using weakly bound stable nuclei [9][10][11][12][13][14][15].…”

“…With this motivation, the excitation function measurements for CF and QEL scattering have been carried out for the projectiles 6 Li and 7 Li with different breakup thresholds (1.67 and 2.47 MeV, respectively) on an 197 Au target over the wide energy range of 0.7 E/V b 1.5. The choice of target was also influenced by the fact that data for fusion of halo nuclei, namely, 6 He + 197 Au [18] and 8 He + 197 Au [4], are available. Initial fusion results have been reported in Ref.…”

“…III A. A comparison of fusion cross sections of the weakly bound stable nuclei 6,7 Li and halo nuclei 6,8 He on 197 Au target is presented. In addition, excitation functions for the ICF and transfer channels obtained from the off-line as well as the online γ -counting measurement are presented in this section.…”