Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Probing nobelium with laser light

27.06.2018

Sizes and shapes of nuclei with more than 100 protons were so far experimentally inaccessible. Laser spectroscopy is an established technique in measuring fundamental properties of exotic atoms and their nuclei. For the first time, this technique was now extended to precisely measure the optical excitation of atomic levels in the atomic shell of three isotopes of the heavy element nobelium, which contain 102 protons in their nuclei and do not occur naturally. This was reported by an international team lead by scientists from GSI Helmholtzzentrum für Schwerionenforschung.

Nuclei of heavy elements can be produced at minute quantities of a few atoms per second in fusion reactions using powerful particle accelerators. The obtained results are well described by nuclear models, which suggest the nuclei to have a bubble-like structure with lower density in their center than at their surface. The results were published in a recent article in Physical Review Letters.


Inner part of the gas-filled optical cell for laser spectroscopy of nobelium isotopes.

M. Laatiaoui, GSI


Gas-filled optical cell for laser spectroscopy of nobelium isotopes.

G. Otto, GSI

Atoms consist of a positively charged nucleus surrounded by an electron shell. The inner electrons penetrate the volume of the nucleus and thus atomic level energies are influenced by the size and shape of the atomic nucleus. A difference in size of two different atomic nuclei resulting, for example, from a different number of neutrons results in a small shift of electronic energy levels.

Precise measurements of these energies are possible using laser light. Energy shifts are traced by varying the frequency and correspondingly the color of the light required to excite electrons to higher energy levels. So far, this method could only be applied to isotopes of lighter elements which are produced at larger production rates and whose atomic structure was already known from experiments with abundant long-lived or stable isotopes.

Nuclei of elements above fermium (Fm, Z=100) can be produced at minute quantities of a few atoms per second in fusion reactions and generally exist only for at most a few seconds. Therefore, their atomic structure was so far not accessible with laser spectroscopic methods.

In the current experiments, nobelium isotopes were produced by fusion of calcium ions with lead at the velocity filter SHIP at GSI’s accelerator facility. To enable laser spectroscopy, the high energetic nobelium atoms were stopped in argon gas. The results are based on a preceding experiment also conducted at GSI, exploring the atomic transitions of nobelium (No). The chemical element with atomic number 102 was discovered about 60 years ago.

The recent experiment investigated the isotopes No-254, No-253 and No-252 which differ in the number of constituent neutrons in their nuclei, with laser spectroscopy. The rates available for the experiment reached values below one ion per second for the isotope No-252.

From the measurements of the excitation frequency for the individual isotopes, the shift in color of the required laser light was determined for No-252 and No-254. For No-253, the fragmentation of the line into several hyperfine components induced by the single unpaired odd neutron was also resolved. The sizes and the shapes of the atomic nuclei were deduced from using theoretical calculations of the atomic structure of nobelium, which were carried out in collaboration with scientists from the Helmholtz Institute Jena in Germany, the University of Groningen in the Netherlands, and the University of New South Wales in Sydney, Australia.

The results confirm that the nobelium isotopes are not spherical but are deformed like an American football. The measured change in size is consistent with nuclear model calculations performed by scientists from GSI and from the Michigan State University in the USA. These calculations predict that the studied nuclei feature a lower charge density in their center than at their surface.

Thanks to these pioneering studies, further heavy nuclides will be accessible for laser spectroscopic techniques, enabling a systematic investigation of changes in size and shape in the region of heavy nuclei. These experiments are so far only possible at GSI and allow for a unique in-depth understanding of the atomic and nuclear structure of the heaviest elements. The results also play a role for the future facility FAIR (Facility for Antiproton and Ion Research), which is currently under construction at GSI. The same techniques and methods could also be employed in the low-energy branch of FAIR’s super fragment separator.

The experiments were conducted by an international team of scientists from GSI Helmholtzzentrum für Schwerionenforschung, Johannes Gutenberg-University Mainz, Helmholtz institute Mainz, TU Darmstadt, KU Leuven (Belgium), University of Liverpool (UK) und TRIUMF (Vancouver, Canada).

Weitere Informationen:

https://www.gsi.de/en/start/news/details/2018/06/27/probing_nobelium_with_laser_...
https://doi.org/10.1103/PhysRevLett.120.232503

Dr. Ingo Peter | idw - Informationsdienst Wissenschaft

More articles from Physics and Astronomy:

nachricht Illinois team finds Wigner crystal -- not Mott insulator -- in 'magic-angle' graphene
25.09.2018 | University of Illinois College of Engineering

nachricht Measuring Smallest Magnetic Fields in the Brain Using Diamond and Laser Technology
25.09.2018 | Fraunhofer-Institut für Angewandte Festkörperphysik IAF

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: Working the switches for axon branching

Our brain is a complex network with innumerable connections between cells. Neuronal cells have long thin extensions, so-called axons, which are branched to increase the number of interactions. Researchers at the Max Planck Institute of Biochemistry (MPIB) have collaborated with researchers from Portugal and France to study cellular branching processes. They demonstrated a novel mechanism that induces branching of microtubules, an intracellular support system. The newly discovered dynamics of microtubules has a key role in neuronal development. The results were recently published in the journal Nature Cell Biology.

From the twigs of trees to railroad switches – our environment teems with rigid branched objects. These objects are so omnipresent in our lives, we barely...

Im Focus: Hygiene at your fingertips with the new CleanHand Network

The Fraunhofer FEP has been involved in developing processes and equipment for cleaning, sterilization, and surface modification for decades. The CleanHand Network for development of systems and technologies to clean surfaces, materials, and objects was established in May 2018 to bundle the expertise of many partnering organizations. As a partner in the CleanHand Network, Fraunhofer FEP will present the Network and current research topics of the Institute in the field of hygiene and cleaning at the parts2clean trade fair, October 23-25, 2018 in Stuttgart, at the booth of the Fraunhofer Cleaning Technology Alliance (Hall 5, Booth C31).

Test reports and studies on the cleanliness of European motorway rest areas, hotel beds, and outdoor pools increasingly appear in the press, especially during...

Im Focus: Scientists present new observations to understand the phase transition in quantum chromodynamics

The building blocks of matter in our universe were formed in the first 10 microseconds of its existence, according to the currently accepted scientific picture. After the Big Bang about 13.7 billion years ago, matter consisted mainly of quarks and gluons, two types of elementary particles whose interactions are governed by quantum chromodynamics (QCD), the theory of strong interaction. In the early universe, these particles moved (nearly) freely in a quark-gluon plasma.

This is a joint press release of University Muenster and Heidelberg as well as the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt.

Then, in a phase transition, they combined and formed hadrons, among them the building blocks of atomic nuclei, protons and neutrons. In the current issue of...

Im Focus: Patented nanostructure for solar cells: Rough optics, smooth surface

Thin-film solar cells made of crystalline silicon are inexpensive and achieve efficiencies of a good 14 percent. However, they could do even better if their shiny surfaces reflected less light. A team led by Prof. Christiane Becker from the Helmholtz-Zentrum Berlin (HZB) has now patented a sophisticated new solution to this problem.

"It is not enough simply to bring more light into the cell," says Christiane Becker. Such surface structures can even ultimately reduce the efficiency by...

Im Focus: New soft coral species discovered in Panama

A study in the journal Bulletin of Marine Science describes a new, blood-red species of octocoral found in Panama. The species in the genus Thesea was discovered in the threatened low-light reef environment on Hannibal Bank, 60 kilometers off mainland Pacific Panama, by researchers at the Smithsonian Tropical Research Institute in Panama (STRI) and the Centro de Investigación en Ciencias del Mar y Limnología (CIMAR) at the University of Costa Rica.

Scientists established the new species, Thesea dalioi, by comparing its physical traits, such as branch thickness and the bright red colony color, with the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

"Boston calling": TU Berlin and the Weizenbaum Institute organize a conference in USA

21.09.2018 | Event News

One of the world’s most prominent strategic forums for global health held in Berlin in October 2018

03.09.2018 | Event News

4th Intelligent Materials - European Symposium on Intelligent Materials

27.08.2018 | Event News

 
Latest News

Microbes to fight fatty liver disease

26.09.2018 | Life Sciences

Diversity in the brain – How millions of neurons become unique

26.09.2018 | Life Sciences

Copper-aluminum superatom

26.09.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>