page_title: Hassium
section_title: Discovery
hierarchical_section_title: Hassium / Discovery
context_page_description: Hassium is a chemical element with the symbol Hs and the atomic number 108. Hassium is highly radioactive; the most stable known isotope, ²⁶⁹Hs, has a half-life of approximately 16 seconds. One of its isotopes, ²⁷⁰Hs, has magic numbers of both protons and neutrons for deformed nuclei, which gives it greater stability against spontaneous fission. Hassium is a superheavy element; it has only been produced in a laboratory in very small quantities by fusing heavy nuclei with lighter ones. Natural occurrences of the element have been hypothesised, but none has ever been found.
  The principal innovation that led to the discovery of hassium was the technique of cold fusion, in which the fused nuclei did not differ by mass as much as in earlier techniques. The technique was first tested at the Joint Institute for Nuclear Research in Dubna, Moscow Oblast, Russian SFSR, Soviet Union, in 1974. The first attempts to synthesize element 108 were made in two different experiments at JINR in 1978. More attempts were made at the same venue in 1983 and then in 1984; the latter resulted in a claim that element 108 had been produced.
caption: Scheme of an apparatus for creation of superheavy elements, based on the Dubna Gas-Filled Recoil Separator set up in the Flerov Laboratory of Nuclear Reactions in JINR. The trajectory within the detector and the beam focusing apparatus changes because of a dipole magnet in the former and quadrupole magnets in the latter.[40]