High resolution gamma-ray spectroscopy with a radioactive beam

The γ-rays de-exciting the yrast states in neutron deficient nuclei around A ∼ 55 have been observed from fusion-evaporation reactions induced by an intense radioactive 19Ne beam on a 40Ca target. An array of escape suppressed germanium detectors recorded reaction γ-rays. Background subtraction of radiation from the decay of the beam was achieved using the timing properties of the pulsed beam and through particle detection using the LEDA charged particle array. These data constitute the first use of an on-line separated and accelerated radioactive beam for studies of near yrast nuclear states using fusion-evaporation reactions. Information on the γ-ray yields from evaporation residues, relative to yields with a stable beam, has been obtained and the problems associated with performing such experiments in a highly radioactive background environment have been addressed.