THE ELECTROSTATIC SEPARATOR VASSILISSA PERFORMANCE AND EXPERIMENTAL RESULTS

Within the past seven years the electrostatic separator VASSILISSA [A. V. Yeremin et al., Nucl. Instr, and Meth. A 274 (1989) 528; A 350 (199 4) 608] has been used for the investigations of evaporation residues ( ER) produced in heavy-ion induced complete fusion reactions. Two types of such studies were of specific interest to us, These are the synthe sis of heavy (Z greater than or equal to 100) nuclides and investigati ons of heavy-ion fusion reactions leading to formation of neutron-defi cient nuclei with Z greater than or equal to 82 and high excitation en ergy (60 MeV less than or equal to E less than or equal to 200 MeV). In the course of the experimental work the optimization of the ion-opt ical and other systems of the separator including the improvements in the focal plane detector system has been made. As a result, the separa tion efficiency values ranging from 3 to 30% were achieved for ER's pr oduced in the reactions with heavy ions from C-12 to Ti-48. The suppre ssion factors > 10(19) for the full energy beam particles and > 10(4) for multinucleon transfer reaction products were achieved. The results of the performed experiments illuminating the separator performance a nd future plans of the separator upgrade are briefly presented.