(α,d) reaction on 12C and 13C and weak coupling configurations

Cross sections for the (α,d) reaction on ¹²C and ¹³C were measured at E_α=34.9 MeV in the range of excitation energies up to 11 MeV in ¹⁴N and up to 13 MeV in ¹⁵N. The angular distributions were compared to calculations with the zero-range distorted-wave Born approximation with the assumption of a deuteron-cluster transfer. On the basis of the assumption that the transferred two nucleons are weakly coupled to the target nuclei, correspondences between the transferred angular momenta and the strengths for the two-nucleon pairs were found for the residual nuclei ¹⁴N and ¹⁵N. Effects of the 0d₃₂ shell and a necessity for the tensor force are discussed in terms of the two-nucleon configurations d₃₂p₁₂ and (d₅₂)², respectively.