First superheavy element experiments at the GSI recoil separator TASCA: The production and decay of element 114 in the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi mathvariant="normal">Pu</mml:mi><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>244</mml:mn></mml:mrow></mml:mmultiscripts></mml:math>(<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi mathvariant="normal">Ca</mml:mi><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>48</mml:mn></mml:mrow></mml:mmultiscripts></mml:math>,3-4<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>n</mml:mi></mml:mrow></mml:math>) reaction

Experiments with the new recoil separator, Transactinide Separator and Chemistry Apparatus (TASCA), at the GSI were performed by using beams of $^{48}\mathrm{Ca}$ to irradiate targets of $^{206\ensuremath{-}208}\mathrm{Pb}$, which led to the production of $^{252\ensuremath{-}254}\mathrm{No}$ 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\ensuremath{-}291}$114) were produced in irradiations of $^{244}\mathrm{Pu}$ targets with $^{48}\mathrm{Ca}$ 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\ensuremath{-}291}$114. A new \ensuremath{\alpha}-decay branch in $^{281}\mathrm{Ds}$ was observed, leading to the new nucleus $^{277}\mathrm{Hs}$.

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