Isomer decay tagging in the heavy nuclei: 210Ra and 209Ra

Excited states in 210Ra and 209Ra were populated using the 184W(30Si,xn) reaction at 148 MeV beam energy. Fusion evaporation recoils were selected using the gas-filled spectrometer, SASSYER. Prompt γ rays were detected using Compton-suppressed Ge detectors from the YRAST Ball array surrounding the target. Delayed γ rays, following isomeric decays, were detected at the focal plane of SASSYER with a smaller array of Ge detectors. The decay energy and lifetime for the 8+(πh9/2)n isomer of 210Ra were determined; values for the yrast B(E2;8+→6+) in 210Ra and neighboring nuclei are interpreted within the seniority scheme. This isomer was also used to select γ-rays deexciting levels above the isomeric state in 210Ra. In addition, transitions in 209Ra were identified for the first time. Two high-spin isomers are suggested to exist in this isotope