The discovery of a new chemical element with atomic number Z=117 is reported. The isotopes ²⁹³117 and ²⁹⁴117 were produced in fusion reactions between ⁴⁸Ca and ²⁴⁹Bk. Decay chains involving 11 new nuclei were identified by means of the Dubna gas-filled recoil separator. The measured decay properties show a strong rise of stability for heavier isotopes with Z≥111, validating the concept of the long sought island of enhanced stability for superheavy nuclei.

Synthesis of a New Element with Atomic Number Z=117, Oganessian, Yu. Ts., Abdullin Sh. F., Bailey P. D., Benker D. E., Bennett M. E., Dmitriev S. N., Ezold J. G., Hamilton J. H., Henderson R. A., Itkis M. G., et al. , Phys. Rev. Lett., Apr/2010, Volume 104, Number 14, p.142502, (2010)