HIGH-RESOLUTION GAMMA-RAY SPECTROSCOPY WITH A RADIOACTIVE BEAM

The gamma-rays de-exciting the yrast states in neutron deficient nucle i around A-55 have been observed from fusione-vaporation reactions ind uced by an intense radioactive Ne-19 beam on a Ca-40 target. An array of escape suppressed germanium detectors recorded reaction gamma-rays. Background subtraction of radiation from the decay of the beam was ac hieved using the timing properties of the pulsed beam and through part icle detection using the LEDA charged particle array. These data const itute the first use of an on-line separated and accelerated radioactiv e beam for studies of near yrast nuclear states using fusion-evaporati on reactions. Information on the gamma-ray yields from evaporation res idues, relative to yields with a stable beam, has been obtained and th e problems associated with performing such experiments in a highly rad ioactive background environment have been addressed.