Investigation of 228Th in the (α, α'2n) reaction

The ²³⁰Th(α, α'2n)²²⁸Th reaction at E_α = 56 MeV was used to investigate states of moderately high spin in ²²⁸Th. Conversion electron and e^?-γ coincidence measurements were carried out, where the electrons were detected with an iron-free orange spectrometer. The ground state and low-lying K^π = 0^? rotational bands were observed up to I^π = 14⁺ and 13^?, respectively. The data are interpreted in terms of an ω-expansion for the ground-state rotational band, and an octupole vibrational band distorted by the Coriolis coupling to the K^π ? 1^? excitations for the K^π = 0^? band.