Alpha-particle scattering from 204,206,208Pb and 209Bi at incident energies near the coulomb barrier

Generation of a repulsive dynamic polarization potential by transfer couplings

“…As the bare cluster-folded potential used in our calculations is energy independent, the optical potential parameters of Goldring et al [20] used as input not varying with energy, the DPP obtained from our CRC calculations would appear to contradict the observation of a threshold anomaly for the 9 Be+ 208 Pb system by Woolliscroft et al [15] and be more in accord with the behavior observed by Signorini et al [34] for the 9 Be+ 209 Bi system or Moraes et al [35] for the 9 Be+ 64 Zn system. However, we note that the real part of the DPP is only on average of order 5% of the strength of the bare real potential at the same radius, thus allowing the DPP induced by coupling to other channels, such as transfer reactions with negative Q values, to induce the classic threshold anomaly behavior observed for 7 Li.…”

“…All partial waves up to = 150 were included and the matching radius was set equal to 130 fm, while the radius limiting the range of the continuum bins was 80 fm. The α+ 208 Pb optical potentials required as input to the cluster-folding 9 Be potentials were taken from Goldring et al [20], while the 5 He+ 208 Pb potentials used the same parameters with the real and imaginary diffuseness increased by 0.1 fm in order to take into account the larger radial extent of the 5 He resonance. All calculations described here were carried out using the code FRESCO [21], version FRXY.1i.…”

α-particle production in the scattering of 6He by 208Pb at energies around the Coulomb barrier

“…For the exit channel, 5 He + 209 Pb, the potential was calculated by folding the n + 209 Pb potential from the compilation of Varner et al [42] and the α + 208 Pb potential of Goldring et al [43] with the ground state wave function of 5 He. The latter was represented by an energy bin of a width 1.2 MeV placed at an excitation energy of 0.8 MeV above the 5 He → 4 He + n breakup threshold.…”

Breakup and neutron-transfer effects on6He+206Pb elastic scattering below the Coulomb barrier

“…For the dineutron + 208 Pb optical potential the deuteron potential of Ref. [20] was used and for α + 208 Pb the potential of Goldring et al [21] was used.…”

“…The global nucleon-nucleus potential of Ref. [27] was adopted for the n + 207 Pb optical potential while for α + 207 Pb the optical potential used in the input to the CDCC calculations to generate the 6 He + 208 Pb interactions was employed [21].…”