Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Ion ping pong reveals forces in atomic nuclei

20.06.2013
An international team of scientists has succeeded in determining the binding energies of exotic atomic nuclei by use of a multi-reflection time-of-flight mass spectrometer.

As reported in the journal Nature, important conclusions about the nature of the forces between the protons and neutrons in nuclei can be drawn by comparing the experimental results and new theoretical values. The difficult measurements were made possible by an extension to the precision experiment ISOLTRAP at the European research centre CERN.


Ion ping pong.
Figure: Frank Wienholtz


Schematic Overview of the new ISOLTRAP component for multi-reflection time-of-flight mass spectrometry. The ions are reflected back and forth between the “mirrors” whereby the different ion species are separated. Figure: Frank Wienholtz

The new component, contributed by physicists from the University of Greifswald, reflects ions back and forth like in a ping pong game. Using this method the team was the first to determine the masses of the artificially produced isotopes calcium-53 and calcium-54.

These isotopes play a key role in basic research in nuclear physics. The measurements confirm predictions by theorists from the Technical University of Darmstadt that also account for three-body forces.

From the masses of atomic nuclei one can deduce – via Einstein‘s equation E=mc2 – the energies with which protons and neutrons are bound in the nucleus. Particularly high binding energies are found for nuclei with “magic“ proton and neutron numbers. These special values – 8, 20, 28, 50, 82 und 126 – have been well established for stable nuclei. In the case of exotic systems with short half-lives, however, present knowledge is very limited.
In order to improve the description, theoretical physicists from the Technical University of Darmstadt included three-body forces, which are determined by fits to the lightest elements, hydrogen and helium, only. Calculations at the Jülich Supercomputing Centre enabled them to predict the masses of much heavier calcium isotopes. Besides the known neutron shell closures at 20 and 28 the predictions for the masses show that 32 is an additional magic number.

Atomic nuclei, in which there is an extreme imbalance with respect to the numbers of protons and neutrons, are particularly sensitive to subtle components of nuclear forces. However, measuring such nuclei is extraordinarily difficult, because they can only be produced in tiny numbers and decay immediately, within the blink of an eye. Such particles are delivered as ion beams to the precision mass balance ISOLTRAP by the “isotope factory” ISOLDE at the European research centre CERN.

However, there is another challenge as the ions of interest are in general generated only together with “contaminations”, i.e. particles of similar masses, so-called isobars. Under these conditions Penning ion traps, up to now the micro scales of choice, reach their limits. Multi-reflection time-of-flight mass spectrometers offer an alternative. Such an instrument was provided by the team from the University of Greifswald and installed as part of the ISOLTRAP setup.

After a recent application as a high-resolution mass separator for Penning-trap investigations (see idw press release “Laboratory Mass Measurement deepens Insight into Neutron Star Crusts“ http://idw-online.de/en/news516628) the new device was successfully used to obtain the first mass measurements of calcium-53 and calcium-54.

The principle of time-of-flight mass spectrometry is rather simple: All ions experience the same force and are therefore accelerated to different velocities corresponding to their masses. Thus, after crossing a drift section they reach a detector one after the other – the light ones first and the heavier later. The result is a time-of-flight mass spectrum. Typical drift sections have a length of about a meter. But there is a trick: By use of an “ion mirror” the particles can be reflected and if a second mirror is added drift sections of several kilometres in length can be folded to table-top dimensions.

The ion ping pong of reflecting the particles several thousand times back and forth lasts only a few milliseconds. The procedure is much faster than the Penning-trap experiments and, in addition, needs fewer ions. This was the breakthrough, which allowed the confirmation of the predictions for the exotic calcium isotopes of the Darmstadt theory group. The successful application of the instrument from Greifswald establishes multi-reflection time-of-flight mass spectrometry as a next generation technology for the investigation of atomic nuclei.

The ion-trap setup ISOLTRAP was operated by researchers from CERN, the Max Planck Institute for Nuclear Physics at Heidelberg, the GSI Helmholtz Centre for Heavy Ion Research at Darmstadt as well as from universities at Dresden, Greifswald, Istanbul (Turkey), Leuven (Belgium) and Orsay (France).
Original publication: http://dx.doi.org/10.1038/nature12226
Masses of exotic calcium isotopes pin down nuclear forces
F. Wienholtz, D. Beck, K. Blaum, Ch. Borgmann, M. Breitenfeldt, R.B. Cakirli, S. George, F. Herfurth, J.D. Holt, M. Kowalska, S. Kreim, D. Lunney, V. Manea, J. Menendez, D. Neidherr, M. Rosenbusch, L. Schweikhard, A. Schwenk, J. Simonis, J. Stanja, R. N. Wolf, K. Zuber, Nature 498 (2013)
Contacts

Dipl.-Phys. Frank Wienholtz and Prof. Dr. Lutz Schweikhard
Institute of Physics of the Ernst-Moritz-Arndt University Greifswald
Felix-Hausdorff-Str. 6, 17487 Greifswald, Germany
Telephone +49 3834 86-4700
wienholtz@physik.uni-greifswald.de
lschweik@physik.uni-greifswald.de
http://www6.physik.uni-greifswald.de/index.html
Prof. Dr. Achim Schwenk
Institut für Kernphysik, Theoriezentrum
Technische Universität Darmstadt
Schlossgartenstr. 2, 64289 Darmstadt, Germany
Telephone +49 6151 16-64235
schwenk@physik.tu-darmstadt.de
http://theorie.ikp.physik.tu-darmstadt.de/strongint/
Spokesperson of the ISOLTRAP collaboration
Prof. Dr. Klaus Blaum
Max Planck Institute for Nuclear Physics
Saupfercheckweg 1, 69117 Heidelberg, Germany
Telephone +49 6221 516850
klaus.blaum@mpi-hd.mpg.de
http://www.mpi-hd.mpg.de/blaum/index.de.html

ISOLTRAP’s local coordinator at CERN
Dr. Susanne Kreim
CERN, bat. 3-1-070, 1211 Geneva 23, Switzerland
Telephone +41 22 7672646
susanne.waltraud.kreim@cern.ch
http://isoltrap.web.cern.ch/

Jan Meßerschmidt | idw
Further information:
http://dx.doi.org/10.1038/nature12226
http://www.uni-greifswald.de

More articles from Physics and Astronomy:

nachricht A 100-year-old physics problem has been solved at EPFL
23.06.2017 | Ecole Polytechnique Fédérale de Lausanne

nachricht Quantum thermometer or optical refrigerator?
23.06.2017 | National Institute of Standards and Technology (NIST)

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>