Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

UTK-ORNL-Oslo theorists pin down the proton-halo state in Flourine-17

27.05.2010
UT professor calculates proton halo state in Fluorine-17

A halo may be difficult to acquire in terms of virtue, but it can also be tough to calculate in terms of physics. Thomas Papenbrock, associate professor of physics and astronomy at the University of Tennessee, Knoxville, and his colleagues Gaute Hagen from Oak Ridge National Laboratory and Morten Hjorth-Jensen from the University of Oslo have managed to do just that, however, and report their findings in "Ab-initio computation of the 17F proton-halo state and resonances in A = 17 nuclei," published earlier this month in Physical Review Letters.

A halo nucleus differs from the more traditional nuclei because it has one or more nucleons (protons or neutrons) that are only weakly bound to the nuclear core. Consequently, they drift far away from it, forming, in effect, a halo. These nuclei are difficult to study because their lives are both short (often lasting only milliseconds) and fragile. Halo nuclei appear at the limits of nuclear existence, very near a place called the dripline. This is the perilous territory where the number of protons and the number of neutrons are plotted against each other and one too many of either means the nucleus will not hold together. Halo nuclei also come with a large number of degrees of freedom—independent configurations required to explain how a system is built.

Hagen, Hjorth-Jensen and Papenbrock set out to study flourine-17, a "mirror nucleus" of oxygen-17. Each of these isotopes has an atomic number of 17, but with their protons and neutrons in flipped numbers (flourine-17 has 9 protons and 8 neutrons, while oxygen-17 has 8 protons and 9 neutrons). Part of what makes these nuclei interesting is that they are neighbors of the most abundant and stable isotope of oxygen: oxygen-16. They determine its proton and neutron energies, which are the basic ingredients of the nuclear shell model—the way protons and neutrons are arranged in a nucleus—and are also key to understanding the shell structure in fluorine and oxygen isotopes. Flourine-17, in particular, has a "halo" formed by an excited proton orbiting far away from the oxygen-16 core that plays an important role in nucleosynthesis, the stellar processes that generate the elements that surround us.

The UTK-ORNL-Oslo team used sophisticated methods to work with the 17 interacting particles in this isotope to better understand it. This is called a many-body problem, meaning that whenever there are more than two bodies interacting with one another, it is difficult to pin down precise calculations of the system. Starting at the beginning (or ab initio, in Latin) the team began with a nuclear Hamiltonian, the operator that describes the energy of a system in terms of its momentum and positional coordinates. They also used the coupled-cluster method — a numerical technique that solves such quantum many-body problems — and ORNL's supercomputer Jaguar to successfully complete first-principle calculations of the proton halo state in Fluorine-17. The calculations contain no adjustable parameters and show a computed binding energy (what holds the nucleus together) that closely reflects experimental data.

The more tools scientists have to calculate the properties of nuclei—how long they live, what holds them together, and how they decay—the more clearly they can investigate the limits of nuclear existence, understand phenomenological models of the nucleus, and predict nuclear properties in applied fields like nuclear medicine or stockpile stewardship.

Whitney Holmes | EurekAlert!
Further information:
http://www.utk.edu

Further reports about: Flourine-17 Papenbrock halo nucleus neutrons oxygen isotope protons

More articles from Physics and Astronomy:

nachricht NASA's James Webb Space Telescope completes final cryogenic testing
21.11.2017 | NASA/Goddard Space Flight Center

nachricht Previous evidence of water on mars now identified as grainflows
21.11.2017 | US Geological Survey

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: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Previous evidence of water on mars now identified as grainflows

21.11.2017 | Physics and Astronomy

NASA's James Webb Space Telescope completes final cryogenic testing

21.11.2017 | Physics and Astronomy

New catalyst controls activation of a carbon-hydrogen bond

21.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>