Novel recoil spectrometer for characterising nuclei far from stability

The motivation for and design of a high-sensitivity detector system for gamma-ray and electron-conversion spectroscopy of metastable states in neutron-deficient nuclei are presented. Fusion products from heavy-ion induced reactions will be brought to a focus and implanted at the back of SOLITAIRE, a gas-filled 6.5 Tesla superconducting magnetic solenoid, designed to physically separate fusion products from the competing background of fission products and scattered beam particles. Four high-efficiency, Compton-suppressed germanium detectors and five silicon detectors will be arranged in a close-packed geometry around the implantation site, so that the gamma-ray and electron-conversion decay of metastable (long-lived) states in the fusion products can be studied in a background-free environment with high sensitivity. The spectrometer will be applied initially to the characterisation of triple shape coexistence in the light lead isotopes. The results will provide a major testing ground for the development of mean-field theories used to predict the stability of heavy nuclei