Attempts to chemically investigate element 112

Abstract

Adsorption / Transactinides / Element 112 / ThermochromatographySummary. Two experiments aiming at the chemical investigation of element 112 produced in the heavy ion induced nuclear fusion reaction of 48 Ca with 238 U 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 283 112 for the 238 U( 48 Ca,3n) 283 112 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 283 112. Therefore, these events could not be unambiguously attributed to the decay of 283 112. In contradiction with earlier publications newer reports from FLNR Dubna claim that 283 112 decays by α-particle emission (E α = 9.5 MeV) with t 1/2 = 4 s followed by a SF-decay of 279 Ds (t 1/2 = 0.2 s). Therefore, Experiment II was designed to be sensitive to both claimed decay properties of 283 112. However, during

The generalized liquid drop model alpha-decay formula: Predictability analysis and superheavy element alpha half-lives

“…These investigations aim to test and advance ideas on the extant nuclear structure for heavy and high Coulomb repulsive force containing nuclei. From the stand-point of heavy element chemistry, the isolation and the study of the properties of exotic heavy elements and their compounds serve to provide unique insights into the structure, bonding and reaction energies of massive multiply charged atomic and molecular species [4] Often the main and sometimes the only decay mode of these nuclei is alpha decay.…”

Chemistry of superheavy elements

“…Both lead to stable operation at beam currents of often more than 1 µA (particle). Separator efficiencies of about 60% for element 114 produced in the 48 Ca on 244 Pu reaction at TASCA [130] and still 13% for 265 Sg synthesized in the very asymmetric 22 Ne on 248 Cm reaction at GARIS [79] have been reached.…”

“…This allows nuclide identification through α-spectroscopy with almost 100% efficiency and a very good localization of the deposition temperature along the temperature gradient. More recently, a slightly modified version of COLD was applied at the FLNR in Dubna in series of volatility studies of Cn [40,41,148] and of element 114 [149]. Presently, the most advanced detector of this type is the Cryo Online Multidetector for Physics And Chemistry of Transactinides (COMPACT).…”

Discovery of the Element with Atomic Number 112 (IUPAC Technical Report)

“…But production attempts at Berkeley [30] failed to reproduce the observation. Chemistry experiments in Germany failed to observe the element with atomic number 112 [31]. To confound the situation, there was no anchor tying 283 112 to any known nuclide.…”

“…The GSI collaboration of Hofmann et al [43] This collaboration sought to re-attempt the synthesis of the element with atomic number 112 by the 48 Ca + 238 U fusion reaction that previously had evinced contradictory results [28,30,31,34,44,45] and reported two events with α-energies of 9.52 MeV ascribed to 283 112 and two other events following instead a spontaneous fission branch. The 283 112 lifetime for the four events was 10 s. JWP ASSESSMENT: The more recent Dubna collaborations have performed careful, high-quality studies whose acknowledgment as synthesis of Z = 112 nuclides, especially 283 112, given the significant redundancies including an independent investigation at GSI, appears very likely.…”