A team led by Yuri Oganessian of the Joint Institute for Nuclear Research in Dubna, Russia, reports smashing together calcium-48 — an isotope with 20 protons and 28 neutrons — with berkelium-249, which has 97 protons and 152 neutrons. The collision spit out neutrons to create two isotopes of an element with 117 protons, one with 176 neutrons and the other with 177.
The new, as yet unnamed, element fills the empty space in the periodic table between elements 116 and 118, both of which have been discovered previously.
Most heavy elements are radioactive, with a very short half life. However, some physicists have hypothesized that certain spots in the periodic table might represent “islands of stability” — very heavy elements which had (relatively) long lives. The experimental data from the new element adds some support to this idea.
A paper describing the experiment will appear in a forthcoming edition of Physical Review Letters.
Update, Tuesday, 6 April, 17:20 EDT
The New York Times has an excellent article on the discovery, which gives more background on how and where the research was done.