Copernicium - History - Official Discovery

Official Discovery

Copernicium was first created on February 9, 1996, at the Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, Germany, by Sigurd Hofmann, Victor Ninov et al. This element was created by firing accelerated zinc-70 nuclei at a target made of lead-208 nuclei in a heavy ion accelerator. A single atom (the second was subsequently dismissed) of copernicium was produced with a mass number of 277.

208
82Pb + 70
30Zn → 278
112Cn → 277
112Cn + 1
0n

In May 2000, the GSI successfully repeated the experiment to synthesize a further atom of copernicium-277. This reaction was repeated at RIKEN using the Search for a Super-Heavy Element Using a Gas-Filled Recoil Separator set-up in 2004 to synthesize two further atoms and confirm the decay data reported by the GSI team.

The IUPAC/IUPAP Joint Working Party (JWP) assessed the claim of discovery by the GSI team in 2001 and 2003. In both cases, they found that there was insufficient evidence to support their claim. This was primarily related to the contradicting decay data for the known nuclide rutherfordium-261. However, between 2001 and 2005, the GSI team studied the reaction 248Cm(26Mg,5n)269Hs, and were able to confirm the decay data for hassium-269 and rutherfordium-261. It was found that the existing data on rutherfordium-261 was for an isomer, now designated rutherfordium-261a.

In May 2009, the JWP reported on the claims of discovery of element 112 again and officially recognized the GSI team as the discoverers of element 112. This decision was based on the confirmation of the decay properties of daughter nuclei as well as the confirmatory experiments at RIKEN.

Read more about this topic:  Copernicium, History

Famous quotes containing the words discovery and/or official:

    As the mother of a son, I do not accept that alienation from me is necessary for his discovery of himself. As a woman, I will not cooperate in demeaning womanly things so that he can be proud to be a man. I like to think the women in my son’s future are counting on me.
    Letty Cottin Pogrebin (20th century)

    Well, on the official record you’re my son. But on this post you’re just another trooper. You heard me tell the recruits what I need from them. Twice that I will expect from you.... You’ve chosen my way of life. I hope you have the guts enough to endure it. But put outa your mind any romantic ideas that it’s a way to glory. It’s a life of suffering and of hardship and uncompromising devotion to your oath and your duty.
    James Kevin McGuinness, and John Ford. Lt. Col. Kirby Yorke (John Wayne)