Octupole deformation in Ac227 by single-proton stripping reactions: Ra226(α, t)227Ac and Ra226(3He,d)227Ac

A radioactive Ra226 (t1/2=1600 yr) target was used to study the Ra226(α,t)227Ac and Ra226(3He,d)227Ac reactions at an incident energy of 30 MeV for both the α and He3 particles. These measurements have confirmed most levels observed in earlier decay-scheme studies, and give evidence for 11 additional levels. Several of the new levels were used in the tentative assignment of two Kπ=(5/2± bands. The experimental data are compared with results from the Nilsson model and a nonadiabatic, rigid, reflection-asymmetric rotor (octupole) model. Although the order and spacing of levels in this mass region can be explained better by models that include an octupole deformation, the spectroscopic strengths in Ac227 are in better agreement with those calculated for the reflection-symmetric potential.