First superheavy element experiments at the GSI recoil separator TASCA: The production and decay of element 114 in the 244Pu(48Ca,3-4n) reaction

Experiments with the new recoil separator, Transactinide Separator and Chemistry Apparatus (TASCA), at the GSI were performed by using beams of 48Ca to irradiate targets of 206-208Pb, which led to the production of 252-254No isotopes. These studies allowed for evaluation of the performance of TASCA when coupled to a new detector and electronics system. By following these studies, the isotopes of element 114 (288-291114) were produced in irradiations of 244Pu targets with 48Ca beams at compound nucleus excitation energies around 41.7 and 37.5 MeV, demonstrating TASCA's ability to perform experiments with picobarn-level cross sections. A total of 15 decay chains were observed and were assigned to the decay of 288-291114. A new α-decay branch in 281Ds was observed, leading to the new nucleus 277Hs.