Russian scientists form Joint Institute of Nuclear Research (JINR) and their American colleagues have reported about first successful synthesis of 117^th element of the Mendeleyev periodic table.

The experiment had started in July 2009, when the target, made of berkelium-249, which was synthesized in the United States, arrived to Dubna from Dimitrovgrad. The target was bombarded by calcium-48 ions at U-400 particle accelerating facility, located at JINR. Researches reported about six credible births of 117^th element’s nuclei, thus filling existing gap between 116^th and 118^th elements of the periodic table.

Russian research fellows of the Flerov laboratory of nuclear reaction successfully synthesize new chemical elements since 1960s. During Soviet regime, researchers had synthesized elements number 104, 105, 106, 107, and 108. First superheavy elements with atomic numbers between 112 and 116, and 118 were also synthesized here. Well, the 117^th element is now also synthesized here.

In nature, no elements with atomic numbers (number of protons in nucleus) over 92, in other words, heavier than uranium, exist. Elements, heavier than uranium, can be synthesized in nuclear reactors, while elements, heavier than fermium, which has 100 protons in its nucleus, can appear only in particle accelerators via bombarding a target with heavy ions. When nuclei of the target and bombarding ions fuse, a new element is born.

 

 

In order to synthesize the element number 117, the target, made of berkelium-249, was bombarded by calcium-48 ions in U-400 cyclotron. Berkelium arrived from the United States and was applied over titanium foil, sectors of which were assembled into a target. The U-400 cyclotron, built between 1974 and 1978, accelerates charged particles by means of magnetic field. Beam of accelerated calcium ions leaves cyclotron and hits the target, which rotates very quickly in order to prevent burning. After meeting the foil with berkelium, the beam knocks out atoms, elementary particles, parts of nuclei, and nuclei of a new element, which can be separated by means of gas-filled separator and detected by special detectors.

First nuclei of the 117^th element were synthesized in 2009, however scientists needed some time to check everything and analyze received data. Scientists finally reported about successful synthesis of three isotopes of a new element, as well as new isotopes of elements 115, 113, 111, 109, 107, and 105. For international acknowledgement of this result, the experiment should be repeated independently by another laboratory, which usually takes some time. After such confirmation, the application is submitted to International Union of Pure and Applied Chemistry (IUPAC), which then authorizes scientists to suggest a name for a new element. The name should sound good in all languages.

Researchers plant to continue studying chemical properties of the 113^th element, in previous experiment with element 117 lived for 5.5 seconds – much longer than in any other experiment. For this purpose researchers have built a new experimental unit for transporting volatile reaction products (113^th element is expected to be volatile) into detecting module, able to register presence of single atoms. The experiments are scheduled to start in April-May 2010.

Russian physicists are going to continue their work with superheavy elements and concentrate on synthesis of elements with more than 118 protons in their nucleus. For this purpose, the accelerator should be modernized, and new separator should be built. Experiments are expected to start in 2012.

Source: RIA Novosti

Kizilova Anna