beta decay of 228Ra and possible level structures in 228Ac.

An iron-free beta spectrometer with pre- and post-acceleration of electrons was used to study {beta} branches and conversion electrons at very low energies in the {beta} decay of {sup 228}Ra. Results of conversion-electron and {gamma}-ray spectroscopy are analyzed using {beta} selection rules and two-quasiparticle-rotor model considerations. A tentative {sup 228}Ac level scheme, including model-dependent spin-parity and configuration assignments consistent with the available data, is presented.