Wien filter for cooled low-energy radioactive ion beams

A Wien filter for cooled radioactive ion beams has been designed at Ion Guide Isotope Separator On Line technique (IGISOL). The purpose of such device is to eliminate doubly charged ions from the mass separated singly charged ions, based on q = +2-->q = +1 charge exchange process in an ion cooler, The performance of the Wien filter has been tested off-line with a discharge ion source as well as on-line with a radioactive beam. The electron capture process of cooled q = 2 ions has been investigated in a radiofrequency quadrupole ion cooler with varying partial pressures of nitrogen. Also, the superasymmetric fission production yields of 68<A<78 nuclei have been deduced. (C) 2002 Published by Elsevier Science B.V.