Attempts to chemically investigate element 112

Two experiments aiming at the chemical investigation of element 112 produced in the heavy ion induced nuclear fusion reaction of ⁴⁸Ca with ²³⁸U were performed at the Gesellschaft für Schwerionenforschung (GSI), Darmstadt, Germany. Both experiments were designed to determine the adsorption enthalpy of element 112 on a gold surface using a thermochromatography setup. The temperature range covered in the thermochromatography experiments allowed the adsorption of Hg at about 35 °C and of Rn at about -180 °C. Reports from the Flerov Laboratory for Nuclear Reactions (FLNR), Dubna, Russia claim production of a 5-min spontaneous fission (SF) activity assigned to ²⁸³112 for the ²³⁸U(⁴⁸Ca,3n) ²⁸³112 reaction. Hence, Experiment I was designed to detect spontaneously fissioning (SF) isotopes of element 112 with half-lives (t_1/2) longer than about 20 s. 11 high-energy events were detected. 7 events exhibit a deposition pattern resembling a chromatographic peak in the vicinity of Rn deposition. However, the energy of the events observed in Experiment I was lower than expected for a SF-decay of ²⁸³112. Therefore, these events could not be unambiguously attributed to the decay of ²⁸³112. In contradiction with earlier publications newer reports from FLNR Dubna claim that ²⁸³112 decays by α-particle emission (E_α = 9.5 MeV) with t_1/2 = 4 s followed by a SF-decay of ²⁷⁹Ds (t_1/2 = 0.2 s). Therefore, Experiment II was designed to be sensitive to both claimed decay properties of ²⁸³112. However, during this experiment neither short α-SF correlations nor SF coincidences were detected. The conclusion is that ²⁸³112 was not unambiguously detected, neither in Experiment I nor in Experiment II.