Resonances and collisional properties of neutron-rich helium isotopes in the adiabatic hyperspherical representation

This work treats few-body systems consisting of neutrons interacting with a ⁴He nucleus. The adiabatic hyperspherical representation is utilized to solve the N-body Schrödinger equation for the three- and four-body systems, treating both ⁶He and ⁷He nuclei. A simplified central potential model for the ⁴He-n interaction is used in conjunction with a spin-dependent three-body interaction to reproduce ⁶He bound-state and resonance properties as well as properties for the ⁸He nucleus in its ground-state. With this Hamiltonian, the adiabatic hyperspherical representation is used to compute bound and scattering states for both ⁶He and ⁷He nuclei. For the ⁶He system, the electric quadrupole transition between the 0⁺ and 2⁺ state is investigated. For the ⁷He system, ⁶He+n elastic scattering is investigated along with the four-body recombination process ⁴He+n+n+n→⁶{He}+n$ and breakup process $⁶{He}+n→⁴He+n+n+n.