E-CDCC and DEA, two eikonal-based reaction models are compared to CDCC at low energy (e.g. 20AMeV) to study their behaviour in the regime at which the eikonal approximation is supposed to fail. We confirm that these models lack the Coulomb deflection
of the projectile by the target. We show that a hybrid model, built on the CDCC framework at low angular momenta and the eikonal approximation at larger angular momenta gives a perfect agreement with CDCC. An empirical shift in impact parameter can also be used reliably to simulate this missing Coulomb deflection.
The astrophysical factor of $^8$B($p$,$gamma$)$^9$C at zero energy, $S_{18}(0)$, is determined by a three-body coupled-channels analysis of the transfer reaction $^{8}$B($d$,$n$)$^{9}$C at 14.4 MeV/nucleon. Effects of the breakup channels of $d$ and
$^9$C are investigated with the continuum-discretized coupled-channels method. It is found that, in the initial and final channels, respectively, the transfer process through the breakup states of $d$ and $^9$C, its interference with that through their ground states in particular, gives a large increase in the transfer cross section. The finite-range effects with respect to the proton-neutron relative coordinate are found to be about 20%. As a result of the present analysis, $S_{18}(0)=22 pm 6~{rm eV~b}$ is obtained, which is smaller than the result of the previous distorted-wave Born approximation analysis by about 51%.
Extensions of the eikonal approximation to low energy (20MeV/nucleon typically) are studied. The relation between the dynamical eikonal approximation (DEA) and the continuum-discretized coupled-channels method with the eikonal approximation (E-CDCC)
is discussed. When Coulomb interaction is artificially turned off, DEA and E-CDCC are shown to give the same breakup cross section, within 3% error, of $^{15}$C on $^{208}$Pb at 20MeV/nucleon. When the Coulomb interaction is included, the difference is appreciable and none of these models agrees with full CDCC calculations. An empirical correction significantly reduces this difference. In addition, E-CDCC has a convergence problem. By including a quantum-mechanical correction to E-CDCC for lower partial waves between $^{15}$C and $^{208}$Pb, this problem is resolved and the result perfectly reproduces full CDCC calculations at a lower computational cost.
How to extract an electric dipole (E1) breakup cross section sigma(E1) from one- neutron removal cross sections measured by using 12C and 208Pb targets, sigma_(-1n)^C and sigma_(-1n)^Pb, respectively, is discussed. It is shown that within about 5% er
ror, sigma(E1) can be obtained by subtracting Gamma sigma_(-1n)^C from sigma_(- 1n)^Pb, as assumed in preceding studies. However, for the reaction of weakly-bound projectiles, the scaling factor Gamma is found to be two times as large as that usually adopted. As a result, we obtain 13-20% smaller sigma(E1) of 31Ne at 250 MeV/nucleon than extracted in a previous analysis of experimental data. By compiling the values of Gamma obtained for several projectiles, Gamma=(2.30 +/- 0.41)exp(- S_n)+(2.43 +/- 0.21) is obtained, where S_n is the neutron separation energy. The target mass number dependence of the nuclear parts of the one-neutron removal cross section and the elastic breakup cross section is also investigated.
The astrophysical factor of the 8B(p,gamma)9C at zero energy, S18(0), is determined from three-body model analysis of 9C breakup processes. The elastic breakup 208Pb(9C,p8B)208Pb at 65 MeV/nucleon and the one-proton removal reaction of 9C at 285 MeV/
nucleon on C and Al targets are calculated with the continuum-discretized coupled-channels method (CDCC) and the eikonal reaction theory (ERT), respectively. The asymptotic normalization coefficient (ANC) of 9C in the p-8B configuration extracted from the two reactions show good consistency, in contrast to in the previous studies. As a result of the present analysis, S18(0) = 66 pm 10 eVb is obtained.
