Acceleration and mass-separation of radioactive ion beams in an isochronous cyclotron

The authors report on first operational results obtained with the two-cyclotron concept for the production and acceleration of a /sup 13 /N radioactive beam (/b T//sub 1/2/=10 min.). A pure beam of 70 particle pA of /sup 13/N at 0.63 meV/amu has been accelerated and used for cross-section measurements of the /sup 1/H(/sup 13 /N, gamma )/sup 14/O reaction which is involved in astrophysical processes. Although the /sup 13/N beam is accelerated with a /sup 13/C beam at least 10/sup 3/ times more intense, the specific characteristics of a cyclotron make it possible to separate clearly these two species whose relative mass difference is only 1.8*10/sup -4/, without loss of intensity for the /sup 13 /N beam. The /sup 13/C contamination on the final target is less than 1 particle pA. The advantages of a cyclotron over a linac as a post-accelerator for low-energy radioactive beams are discussed.