Absolute transmission and separation properties of the gas-filled recoil separator RITU

The absolute transmission values of the RITU gas-filled recoil separator have been measured for several fusion evaporation products. Three different beams and several targets were used to create fusion evaporation residues in mass region A=170–190 mainly in neutron evaporation channels. Measured absolute transmission values from around 7% up to round about 90% have been observed for very asymmetric and symmetric reactions, respectively. For the reactions studied it was observed that the angular spread of products after the target and the angular acceptance of RITU determine the transmission probability relatively accurately. Magnetic rigidities and equilibrium charges of the product ions were seen to systemically decrease and increase, respectively, with increasing gas pressure. The comparison of observed equilibrium charges to various formulae is carried out. Clear minima of image width were found in case of asymmetric reactions as a function of gas pressure. Effects of the position of an additional movable beam stopper and the field strength of the first quadrupole magnet on transmission have been studied and are reported.