Artificial radioactive element properties unknown	memory peg
	2004 Ю.Ц. Оганесян (Yu.Ts. Oganessian) and co-workers, Dubna, Russia
	un-un-pent-ium = 1-1-5-ium

Scientists from the Glenn T. Seaborg Institute and the Chemical Biology and Nuclear Science Division at the Lawrence Livermore National Laboratory, in collaboration with researchers from the Joint Institute for Nuclear Research in Russia (JINR), have discovered the two newest super heavy elements, element 113 and element 115.

In experiments conducted at the JINR U400 cyclotron with the Dubna gas-filled separator between July 14 and Aug. 10, 2003, the team of scientists observed atomic decay patterns, or chains, that confirm the existence of element 115 and element 113. In these decay chains, element 113 is produced via the alpha decay of element 115.

The results have been accepted for publication in the Feb. 1, 2004 issue of Physical Review C.

The element does not have a name yet, therefore the systematic IUPAC name is used (system explained at Ununoctium).

Abstract:

Oganessian Yu.Ts. et al.
Experiments on the synthesis of element 115 in the reaction ²⁴³Am (⁴⁸Ca, xn)^291-x115

The results of experiments designed to synthesize element 115 isotopes in the ²⁴³Am (⁴⁸Ca, xn)^291-x115 reaction are presented. With a beam dose of 4.3x10¹⁸ 248-MeV ⁴⁸Ca projectiles, we observed three similar decay chains consisting of five consecutive α-decays, all detected in time intervals of about 20 s and terminated at a later time by a spontaneous fission with a high energy release (TKE~220 MeV). At a higher bombarding energy of 253 MeV, with an equal ⁴⁸Ca beam dose, we registered a different decay chain of four consecutive α-decays detected in a time interval of about 0.5 s, also terminated by spontaneous fission. The α-decay energies and half-lives for nine new α-decaying nuclei were determined. The decay properties of these synthesized nuclei are consistent with consecutive α-decays originating from the parent isotopes of the new element 115, ²⁸⁸115 and ²⁸⁷115, produced in the 3n- and 4n-evaporation channels with cross sections of about 3 pb and 1 pb, respectively. The radioactive properties of the new odd-Z nuclei (105-115) are compared with the predictions of the macroscopic-microscopic theory. The experiments were carried out at the U400 cyclotron with the recoil separator DGFRS at FLNR, JINR.
The investigation has been performed at the Flerov Laboratory of Nuclear Reactions, JINR.
Preprint of the Joint Institute for Nuclear Research. Dubna, 2003

Further reading:

• Livermore Scientists Team With Russia To Discover Elements 113 and 115, Press Release 2 February 2004.
• Yu. Ts. Oganessian et al., Experiments on the synthesis of element 115 in the reaction ²⁴³Am (⁴⁸Ca, xn)^291-x115. Submitted to Physical Review C (PDF file on-line).