Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


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


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.

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.

A view into the 120-meter long linear accelerator at GSI, which accelerated the calcium-ions used to produce element 117.
(credit: GSI)
The TransActinide Separator and Chemistry Apparatus (TASCA) at GSI Darmstadt is a highly efficient device for studying superheavy elements.
(credit: GSI)
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)
Rose Boll conducts chemical separation and purification for berkelium-249 production at ORNL's Radiochemical Engineering Development Center.
(credit: Oak Ridge National Laboratory)
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

GSI Helmholtz Centre for Heavy Ion Research
Planckstr. 1
D 64291 Darmstadt, GERMANY
phone +49 6159 71-2462
fax +49 6159 71-3463

Weitere Informationen:

Petra Giegerich | idw - Informationsdienst Wissenschaft

More articles from Life Sciences:

nachricht North and South Cooperation to Combat Tuberculosis
22.03.2018 | Universität Zürich

nachricht Researchers Discover New Anti-Cancer Protein
22.03.2018 | Universität Basel

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Researchers Discover New Anti-Cancer Protein

An international team of researchers has discovered a new anti-cancer protein. The protein, called LHPP, prevents the uncontrolled proliferation of cancer cells in the liver. The researchers led by Prof. Michael N. Hall from the Biozentrum, University of Basel, report in “Nature” that LHPP can also serve as a biomarker for the diagnosis and prognosis of liver cancer.

The incidence of liver cancer, also known as hepatocellular carcinoma, is steadily increasing. In the last twenty years, the number of cases has almost doubled...

Im Focus: Researchers at Fraunhofer monitor re-entry of Chinese space station Tiangong-1

In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.

Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...

Im Focus: Alliance „OLED Licht Forum“ – Key partner for OLED lighting solutions

Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.

They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...

Im Focus: Mars' oceans formed early, possibly aided by massive volcanic eruptions

Oceans formed before Tharsis and evolved together, shaping climate history of Mars

A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...

Im Focus: Tiny implants for cells are functional in vivo

For the first time, an interdisciplinary team from the University of Basel has succeeded in integrating artificial organelles into the cells of live zebrafish embryos. This innovative approach using artificial organelles as cellular implants offers new potential in treating a range of diseases, as the authors report in an article published in Nature Communications.

In the cells of higher organisms, organelles such as the nucleus or mitochondria perform a range of complex functions necessary for life. In the networks of...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

Latest News

Modular safety concept increases flexibility in plant conversion

22.03.2018 | Trade Fair News

New interactive map shows climate change everywhere in world

22.03.2018 | Earth Sciences

New technologies and computing power to help strengthen population data

22.03.2018 | Earth Sciences

Science & Research
Overview of more VideoLinks >>>