First attempt to chemically identify element 112

Abstract

The first attempt to chemically identify one of the recently discovered long-lived isotopes of superheavy elements, namely 283112 (3 min, SF), made at FLNR, Dubna is reported. The nuclide was produced by fusion of accelerated 48Ca with a target of natural U, which contained some Nd to simultaneously produce also short-lived Hg nuclides. According to test experiments with Hg, the expected lighter homologue of element 112, both elements can be isolated from the products of the bombardment in metallic state, and transported from the target in flowing He gas to a detection system, where spontaneous fission and alpha decays 49-s 185Hg) were registered using PIPS detectors. The surface of the detectors was covered with a thin layer of Au or Pd which ensured the detection of Hg with high efficiency due to its chemisorption on these surfaces. While about three SF events could be expected, not a single one was detected at an upper limit for the production cross section of about one picobarn. This may point to a "Rn-like" rather than "Hg-like" behavior of element 112. A new experiment is planned, in which both a "Rn-like" and a "Hg-like" species could be detected.