Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Approaching the island of stability: observation of the superheavy element 117

02.05.2014

Several atoms of the superheavy element with atomic number 117 have been created and observed by an international collaboration working at the GSI accelerator laboratory in Germany.

The measured decay properties match previous data, strengthening the case for official recognition of 117 as a new element. New findings obtained in the present work mark an important step towards the capability to observe still more long-lived superheavy nuclei, as expected to exist on the 'island of stability' of superheavy elements.


A view into the 120-meter long linear accelerator at GSI, which accelerated the calcium-ions used to produce element 117. (credit: GSI)

The periodic table of the elements is to get crowded towards its heaviest members. Evidence for the artificial creation of element 117 has recently been obtained at the GSI Helmholtz Centre for Heavy Ion Research, an accelerator laboratory located in Darmstadt, Germany. The experiment was performed by an international team of chemists and physicists headed by Prof. Christoph Düllmann, who holds positions at GSI, Johannes Gutenberg University Mainz (JGU), and the Helmholtz Institute Mainz (HIM). The team included 72 scientists and engineers from 16 institutions in Australia, Finland, Germany, India, Japan, Norway, Poland, Sweden, Switzerland, the United Kingdom, and the United States.

Elements beyond atomic number 104 are referred to as superheavy elements. The most long-lived ones are expected to be situated on a so-called 'island of stability', where nuclei with extremely long half-lives should be found. Although superheavy elements have not been found in nature, they can be produced by accelerating beams of nuclei and shooting them at the heaviest possible target nuclei. Fusion of two nuclei – a very rare event – occasionally produces a superheavy element. Those currently accessible generally only exist for a short time. Initial reports about the discovery of an element with atomic number 117 were released in 2010 from a Russia-U.S. collaboration working at the Joint Institute for Nuclear Research in Dubna, Russia.

In a powerful example of international collaboration, this new measurement required close coordination between the accelerator and detection capabilities at GSI in Germany and the unique actinide isotope production and separation facilities at Oak Ridge National Laboratory (ORNL) in the U.S. The special berkelium target material, essential for the synthesis of element 117, was produced over an 18-month-long campaign. This required intense neutron irradiation at ORNL's High Flux Isotope Reactor, followed by chemical separation and purification at ORNL's Radiochemical Engineering Development Center. Approximately 13 milligrams of the highly-purified isotope Bk-249, which itself decays with a half-life of only 330 days, were then shipped to Mainz University. There, the facilities and expertise are available to transform the exotic radioisotope into a target, able to withstand the high-power calcium-ion beams from the GSI accelerator. Atoms of element 117 were separated from huge numbers of other nuclear reaction products in the TransActinide Separator and Chemistry Apparatus (TASCA) and were identified through their radioactive decay. These measured chains of alpha-decays produced isotopes of lighter elements with atomic numbers 115 to 103, whose registration added to the proof for the observation of element 117.

In the decay chains, both a previously unknown alpha-decay pathway in Db-270 (dubnium – element 105) and the new isotope Lr-266 (lawrencium – element 103) were identified. With half-lives of about one hour and about 11 hours, respectively, they are among the longest-lived superheavy isotopes known to date. As unwanted background events are present in all superheavy element experiments, the longer-lived an isotope is, the harder is its reliable identification. The present experiment, for which TASCA was significantly upgraded to better separate unwanted background products and thus to allow more sensitive identification of superheavy nuclei, proved that their reliable identification is now possible.

"This is of paramount importance as even longer-lived isotopes are predicted to exist in a region of enhanced nuclear stability", explains Christoph Düllmann.

Prof. Horst Stöcker, Scientific Director of GSI, adds: "The successful experiments on element 117 are an important step on the path to the production and detection of elements situated on the 'island of stability' of superheavy elements."

"This is an important scientific result and a compelling example of international cooperation in science, advancing superheavy element research by leveraging the special capabilities of national laboratories in Germany and the U.S.," said ORNL Director Thom Mason.

Element 117 is yet to be named: a committee comprising members of the International Unions of Pure and Applied Physics and Chemistry will review these new findings, along with the original ones, and decide whether further experiments are needed before acknowledging the element's discovery. Only after such final acceptance, a name may be proposed by the discoverers.

Publication:
J. Khuyagbaatar et al.
48Ca + 249Bk Fusion Reaction Leading to Element Z = 117: Long-Lived α-Decaying
270Db and Discovery of 266Lr
Physical Review Letters, 112 (2014) 172501
DOI: 10.1103/PhysRevLett.112.172501

Work performed by Oak Ridge National Laboratory was supported by the U.S. Department of Energy, Office of Science. UT-Battelle manages ORNL for DOE's Office of Science.

Images:
http://www.uni-mainz.de/bilder_presse/09_kernchemie_117_01.jpg
A view into the 120-meter long linear accelerator at GSI, which accelerated the calcium-ions used to produce element 117.
(credit: GSI)

http://www.uni-mainz.de/bilder_presse/09_kernchemie_117_02.jpg
The TransActinide Separator and Chemistry Apparatus (TASCA) at GSI Darmstadt is a highly efficient device for studying superheavy elements.
(credit: GSI)

http://www.uni-mainz.de/bilder_presse/09_kernchemie_117_03.jpg
The blue glow of Cherenkov radiation is visible in the reactor pool at ORNL's High Flux Isotope Reactor (HFIR) during a fuel change-out. Intense irradiation at HFIR, followed by chemical separation and purification, produced the necessary berkelium target material for the element 117 experiment.
(credit: Oak Ridge National Laboratory)

http://www.uni-mainz.de/bilder_presse/09_kernchemie_117_04.jpg
Rose Boll conducts chemical separation and purification for berkelium-249 production at ORNL's Radiochemical Engineering Development Center.
(credit: Oak Ridge National Laboratory)

http://www.uni-mainz.de/bilder_presse/09_kernchemie_117_05.gif
Target wheel produced at the Institute of Nuclear Chemistry at Johannes Gutenberg University Mainz, containing the berkelium-249.
(credit: GSI)

Further information:
Professor Dr. Christoph Düllmann
Institute for Nuclear Chemistry
Johannes Gutenberg University Mainz
D 55099 Mainz, GERMANY
phone +49 6131 39-25852
fax +49 6131 39-20811
e-mail: duellmann@uni-mainz.de
http://www.kernchemie.uni-mainz.de/eng/index.php

GSI Helmholtz Centre for Heavy Ion Research
Planckstr. 1
D 64291 Darmstadt, GERMANY
phone +49 6159 71-2462
fax +49 6159 71-3463
e-mail: C.E.Duellmann@gsi.de
https://www.gsi.de/en/start/news.htm

Weitere Informationen:

http://www.superheavies.de/
http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.112.172501

Petra Giegerich | idw - Informationsdienst Wissenschaft

More articles from Life Sciences:

nachricht Not of Divided Mind
19.01.2017 | Hertie-Institut für klinische Hirnforschung (HIH)

nachricht CRISPR meets single-cell sequencing in new screening method
19.01.2017 | CeMM Forschungszentrum für Molekulare Medizin der Österreichischen Akademie der Wissenschaften

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

New Study Will Help Find the Best Locations for Thermal Power Stations in Iceland

19.01.2017 | Earth Sciences

Not of Divided Mind

19.01.2017 | Life Sciences

Molecule flash mob

19.01.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>