The Discovery of Element 112 - proposed name COPERNICIUM


9 February 1996

The element 112 (277112) has been produced for the first time in fusion reactions of  70Zn (proton number 30) projectiles with  208Pb (proton number 82) targets. The formed compound nucleus 278112 deexcites by emitting a neutron and results in the isotope 277112.
We observed one nucleus of element 112 in a three weeks experiment which ran 24 hours per day. The nucleus 277112 is radioactive and decays after a few 100 μs by the emission of an alpha particle into the daughter nucleus 273Ds.

https://www.gsi.de/fileadmin/_migrated/pics/decaychain112.png
Figure. 1: The element 112 was identified via this decay chain. All measured α-particle energies and the corresponding decay times are given. (Image source: GSI Helmholtzzentrum für Schwerionenforschung)

 

2004

Japanese researches at RIKEN (Institute of Physical and Chemical Research, Tokyo), confirm the discovery of 277112 with the same fusion reaction 70Zn + 208Pb.

1998 – 2004

Further nuclei of element 112 with larger neutron numbers (282-285112) have been produced at the Flerov Laboratory of Nuclear Research (JINR) in Dubna, Russia in the reaction 48Ca + 238U (20 and 92 protons respectively).

2005 -2007

Four nuclei of 283112 have been produced at SHIP in the reaction 48Ca + 238U.

19 May 2009

The International Union of Pure and Applied Chemistry (IUPAC) assigns the discovery of element 112 to Sigurd Hofmann and his group.
See IUPAC report here.

13 July 2009

The group of Sigurd Hofmann proposes to the IUPAC the name COPERNICIUM (symbol Cp) for element 112.

"With our suggestion we want to honour a scientist, an astronomer, who lived in the period of the transition from the middle ages to modern times. He was born on February 19th, 1473, in Torun, Poland, and died on May 24th, 1543, in Frombork/Frauenburg. His work was of exceptional influence on the political and philosophical thinking of people and on the rise of modern science based on experimental results."

This name will be accepted if no objections are raised within a period of 6 months.