Coupled channels analysis of He+ He scattering and resonant behaviour

Previously measured elastic scattering and two-neutron transfer angular distributions for $^{8}$He scattered from a $^{4}$He target [Phys Lett. B 75, 58-62, 2017] are analysed using the coupled reaction channels (CRC) formalism and the effect of 1, 2 and 4-neutron transfers on both the elastic scattering and $^{6}$He + $^{6}$He channels is examined. The CRC calculations find that 1n and 2n transfers are the dominant processes in the production of $^{6}$He while the influence on the elastic scattering of 4n transfer between the $^{4}$He cores is small. Calculated excitation functions based on fits to both data sets suggest resonant-like behaviour centred at $^{12}$Be excitation energies of about 13 MeV and 14-16 MeV, both associated with the $L=2$ and 4 partial waves and consistent with molecular structures in the intermediate $^{12}$Be system.