Ion-guide isotope separator on-line for heavy ion reactions

The ion-guide technique for on-line isotope separation has been introduced to the existing isotope-separator on-line (ISOL) at INS. Various properties of the ion-guide ISOL have been studied for its future use in heavy-ion reactions. In particular, we have measured the change of relative efficiencies of the system by changing beam intensity in reactions of 27Al(α,2pn)28Al, 19F(12C,2pn)28Al and 12C(19F,2pn)28Al. The result shows that the efficiency can be well expressed in terms of the product of beam intensity and energy loss of beam particles in the helium gas used, and that it decreases rapidly as the above product exceeds 1017 eV/s, indicating an evidence for plasma effect for the first time. A small gas-filled recoil mass separator has also been made at INS and its properties have been studied in detail. A hybrid type of an ISOL system consisting of the recoil separator and the ion-guide ISOL is proposed for the study of short-lived activities produced in heavy-ion reactions such as those formed in target-fragmentation processes. (author)