The Dubna gas-filled recoil separator: status and developments

Within the Dubna-Livermore collaboration a series of experiments were performed. Experiments with the Dubna gas-filled recoil separator have resulted in the discovery of the new nuclides 262Rf, 265Sg, 266Sg, 267Hs, and 273110. The ground state decay properties established for 266Sg and 262Rf revealed an enhancement in their stability against α and spontaneous fission-decays by a factor of ∼103 as compared with that of nuclides with lower Z and N values. A direct test of the theory was the observation of a decrease in stability for nuclides with Z,N beyond the predicted magic numbers. The α-particle energy measured for 273110 with N=163 provided evidence that a neutron shell closure indeed exists and is located at N=162. Concerning the possibility to reach the Z=114 region with gas-filled separator some improvements were made to suppress fast background particles. (author)