[en] Studies of the superheavy elements form one of the pillars of the GSI research program. A unique combination of experimental facilities is installed at the GSI. Various topics, ranging from the synthesis of new elements, spectroscopy experiments to study the nuclear structures of the heaviest nuclei, highly accurate mass measurements beyond uranium, to chemical investigations of elements around element 114 and the synthesis of novel chemical superheavy element compound classes are being studied. This is complemented by fully relativistic quantum chemical calculations. As a recent highlight, the ²⁴⁴Pu(⁴⁸Ca,3-4n)^288,289 114 reaction was studied, leading to the observation of element 114 at the new gas-filled recoil separator TASCA. (orig.)

No abstract available

[en] Currently, gas phase chemistry experiments with heaviest elements are usually performed with the gas-jet technique with the disadvantage that all reaction products are collected in a gas-filled thermalisation chamber adjacent to the target. The incorporation of a physical preseparation device between target and collection chamber opens up the perspective to perform new chemical studies. But this approach requires detailed knowledge of the stopping force (STF) of the heaviest elements in various materials. Measurements of the energy loss of mercury (Hg), radon (Rn), and nobelium (No) in Mylar and argon (Ar) were performed at low kinetic energies of around (40-270) keV per nucleon. The experimentally obtained values were compared with STF calculations of the commonly used program for calculating stopping and ranges of ions in matter (SRIM). Using the obtained data points an extrapolation of the STF up to element 114, eka-lead, in the same stopping media was carried out. These estimations were applied to design and to perform a first chemical experiment with a superheavy element behind a physical preseparator using the nuclear fusion reaction ²⁴⁴Pu(⁴⁸Ca; 3n)²⁸⁹114. One decay chain assigned to an atom of ²⁸⁵112, the α-decay product of ²⁸⁹114, was observed.

[en] The synthesis of element 116 in fusion-evaporation reactions of a ⁴⁸Ca beam with radioactive ²⁴⁸Cm targets was studied at the velocity filter SHIP of GSI in Darmstadt. At excitation energies of the compound nuclei of 40.9MeV, four decay chains were measured, which were assigned to the isotope ²⁹²116, and one chain, which was assigned to ²⁹³116. Measured cross-sections of (3.4_-1.6^+2.7)pb and (0.9_-0.7^+2.1), respectively, and decay data of the chains agree with data measured previously at the Flerov Laboratory of Nuclear Reactions in Dubna. As a new result, one α-decay chain was measured, which terminates after four α decays by spontaneous fission. The α energies of the second-to-fourth decay are considerably higher than those measured for the α decays of ²⁸⁹114, ²⁸⁵Cn, and ²⁸¹Ds and the spontaneous fission half-life is significantly longer than that of ²⁷⁷Hs measured in previous experiments. A possible assignment is discussed in the frame of excited quasiparticle states of nuclei populated in the decay chain from ²⁹³116. Also other possible assignments were considered and are discussed. At an excitation energy of 45.0MeV no events were observed resulting in a one-event cross-section limit of 1.6 pb. The technical aspects related with the use of radioactive target material at SHIP are described in detail. The experience gained in this experiment will serve as a basis for future experiments aiming to study still heavier elements at the velocity filter SHIP. (orig.)