Radioactive ion beam development in Berkeley*

Two radioactive ion beam projects are under development at the 88 ” Cyclotron, BEARS (Berkeley Experiment with Accelerated Radioactive Species) and the 14O experiment. The projects are initially focused on the production of 11C and 14O, but it is planned to expand the program to 17F, 18F, 13N and 76Kr. For the BEARS project, the radioactivity is produced in form of either CO2 or N2O in a small medical 10 MeV proton cyclotron. The activity is then transported through a 300 m long He-jet line to the 88 ” cyclotron building, injected into the AECR-U ion source and accelerated through the 88 ” cyclotron to energies between 1 to 30 MeV / nucleon. The 14O experiment is a new experiment at the 88 ” cyclotron to measure the energy-shape of the beta decay spectrum. For this purpose, a target transfer line and a radioactive ion beam test stand has been constructed. The radioactivity is produced in form of CO in a hot carbon target with a 20 MeV 3He from the 88 ” Cyclotron. The activity diffuses through an 8m long stainless steel line into the 6.4 Ghz ECR ion source IRIS (Ion source for Radioactive ISotopes). It is then ionized and accelerated to 30 keV to mass separate the 14O and then implanted into a carbon foil. In order to optimize the on-line efficiencies of the LBNL ECR ion sources, off-line ionization efficiency studies are carried out for various gases. A summary of the ionization efficiency measurements is presented. 1