Level structure of 221Ac and 217Fr from decay spectroscopy, and reflection asymmetry in 221Ac

225Pa and 221Ac were produced at the IGISOL facility through proton-induced fusion-evaporation reactions and have been studied using & alpha;-particle spectroscopy, as well as & alpha;-& gamma; and & alpha;-electron coincidence spectroscopy. The level scheme of 221Ac, daughter of 225Pa, and of 217Fr, daughter of 221Ac were reconstructed. An interpretation of 221Ac levels as K = 5/2 & PLUSMN; and K = 3/2 & PLUSMN; parity-doublet bands is proposed. Such bands appear in reflection-asymmetric models and would be an indication of a static reflection asymmetric shape for 221Ac.

Automated summary

225Pa and 221Ac were produced and studied at the IGISOL facility using different spectroscopic techniques. The level scheme of 221Ac and its daughter nucleus 217Fr were reconstructed. The interpretation of 221Ac levels as parity-doublet bands suggests a static reflection asymmetric shape for this nucleus.