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 Building a better battery
29.06.2016 | Texas A&M University

nachricht New way out: Researchers show how stem cells exit bloodstream
29.06.2016 | North Carolina State University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Optical lenses, hardly larger than a human hair

3D printing enables the smalles complex micro-objectives

3D printing revolutionized the manufacturing of complex shapes in the last few years. Using additive depositing of materials, where individual dots or lines...

Im Focus: Flexible OLED applications arrive

R2D2, a joint project to analyze and development high-TRL processes and technologies for manufacture of flexible organic light-emitting diodes (OLEDs) funded by the German Federal Ministry of Education and Research (BMBF) has been successfully completed.

In contrast to point light sources like LEDs made of inorganic semiconductor crystals, organic light-emitting diodes (OLEDs) are light-emitting surfaces. Their...

Im Focus: Unexpected flexibility found in odorant molecules

High resolution rotational spectroscopy reveals an unprecedented number of conformations of an odorant molecule – a new world record!

In a recent publication in the journal Physical Chemistry Chemical Physics, researchers from the Max Planck Institute for the Structure and Dynamics of Matter...

Im Focus: 3-D printing produces cartilage from strands of bioink

Strands of cow cartilage substitute for ink in a 3D bioprinting process that may one day create cartilage patches for worn out joints, according to a team of engineers. "Our goal is to create tissue that can be used to replace large amounts of worn out tissue or design patches," said Ibrahim T. Ozbolat, associate professor of engineering science and mechanics. "Those who have osteoarthritis in their joints suffer a lot. We need a new alternative treatment for this."

Cartilage is a good tissue to target for scale-up bioprinting because it is made up of only one cell type and has no blood vessels within the tissue. It is...

Im Focus: First experimental quantum simulation of particle physics phenomena

Physicists in Innsbruck have realized the first quantum simulation of lattice gauge theories, building a bridge between high-energy theory and atomic physics. In the journal Nature, Rainer Blatt‘s and Peter Zoller’s research teams describe how they simulated the creation of elementary particle pairs out of the vacuum by using a quantum computer.

Elementary particles are the fundamental buildings blocks of matter, and their properties are described by the Standard Model of particle physics. The...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Conference ‘GEO BON’ Wants to Close Knowledge Gaps in Global Biodiversity

28.06.2016 | Event News

ERES 2016: The largest conference in the European real estate industry

09.06.2016 | Event News

Networking 4.0: International Laser Technology Congress AKL’16 Shows New Ways of Cooperations

24.05.2016 | Event News

 
Latest News

Building a better battery

29.06.2016 | Life Sciences

New way out: Researchers show how stem cells exit bloodstream

29.06.2016 | Life Sciences

Crucial peatlands carbon-sink vulnerable to rising sea levels

29.06.2016 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>