RECOMBINATION OF LITHIUM-LIKE BISMUTH AND URANIUM IONS WITH FREE-ELECTRONS AT THE ESR

In two separate experiments at the ESR recombination of 230 MeV/u Bi80 + and 170 MeV/u U89+ ions was studied. The analysis of these experimen ts has been carried on in order to extract information about radiative recombination (RR) of very highly charged ions exposed to electrons w ith a density of few 10(6) cm(-3). In the light of the recombination r ate enhancement seen in almost all recent experiments at a relative en ergy E-rel = 0 eV, a surprising result is found for the very highly ch arged ions, which could add some confusion to an already puzzling pict ure: in spite of the high charge state of the investigated ions there is no evidence of enhanced recombination beyond the expected RR rate. This observation appears to be supported by other experimental finding s at the ESR as well. We suspect, however, that this is a consequence of excessive transverse magnetic field components in the ESR cooler (w hich have meanwhile been corrected for) causing variable degrees of an gular mismatch between the ion beam and the electron beam occurring wh en the ring settings are tuned for optimum cooling.