Featured Research

from universities, journals, and other organizations

Exploring an 'island of inversion,' physicists find new clues to element synthesis in supernovae

Date:
February 3, 2011
Source:
Technische Universitaet Muenchen
Summary:
A new discovery, and the questions is raises, could help explain in greater detail how elements are synthesized in the explosion of stars. Although theory predicted a spherical arrangement in the nucleus of magnesium-32, experiments had only revealed a configuration shaped like an American football. Now, through experiments at CERN, physicists have confirmed the existence of a spherical magnesium-32 nucleus, formed at a much lower than predicted energy level.

A new discovery, and the questions it raises, could help explain in greater detail how elements are synthesized in stellar explosions -- such as the supernova that left behind the Crab Nebula.
Credit: VLT/ESO

Elements heavier than iron come into being only in powerful stellar explosions, supernovae. During nuclear reactions all kinds of short-lived atomic nuclei are formed, including more stable combinations -- the so-called magic numbers -- predicted by theory. Yet here, too, there are exceptions: the islands of inversion. Headed by physicists from the Excellence Cluster Universe at the Technische Universitaet Muenchen (TUM), an international team of scientists has now taken a closer look at the island that was first discovered.

Related Articles


They have now published their results in Physical Review Letters.

All chemical elements known on earth come from space. The most common elements in the universe, hydrogen and helium, were created shortly after the Big Bang. Other elements, such as carbon and oxygen, came into existence later, through the fusion of atomic nuclei inside stars. Elements heavier than iron owe their emergence to gigantic stellar explosions, known as supernovae. These include, for instance, the precious metals gold and silver or the radioactive uranium.

The cauldron of a supernova gives birth to a whole array of high-mass atomic nuclei, which decay to stable elements via different short-lived intermediate stages. Analogous to the shell model for electrons, nuclear physicists developed a model that predicts particularly high stability for specific combinations in the number of neutrons and protons. These are the "magic numbers": the shells are full and the nuclei nearly spherical.

However, there are "magic" nuclei that deviate from the expected shell structure. An international collaboration under the direction of physicists from the Cluster of Excellence Origin and Structure of the Universe at the TUM took a closer look at the nuclei in a domain with the magic neutron number 20, also known as the "island of inversion." Their measurements with REX-ISOLDE, an accelerator for radioactive ion beams at CERN, led to surprising results.

In their experiment the scientists studied the neutron-rich isotope magnesium-32 by shooting a magnesium-30 beam at a titanium film loaded with tritium, a radioactive isotope of hydrogen. In a so-called pair transfer reaction, two neutrons are knocked off the tritium and transferred to the magnesium nucleus, thus turning it into magnesium-32.

The neutron-rich isotope magnesium-32, whose nucleus has 20 neutrons and 12 protons, is supposed to be magic and, as such, should have a spherical shape. However, the lowest energy state in magnesium-32 is not spherical, but deformed. The nucleus is reminiscent of an egg-shaped American football. The spherical configuration was not supposed to ensue until higher states of energy were reached.

For the first time ever, the scientists succeeded in confirming the existence of the spherical magnesium-32 nucleus. What's more, the spherical magnesium-32 nucleus was generated at a much lower energy level than theoretically predicted. This result has yet again put a question mark on the theoretical models describing changes in shell structure in this and other regions of the table of nuclides.

"We were overjoyed to have finally succeeded in confirming the existence of the spherical magnesium-32 nucleus," says Professor Kruecken, Chair of Hadrons and Nuclear Physics at the TU Muenchen. "But these insights present new challenges to us physicists. In order to be able to predict the exact course of element synthesis in stellar explosions, we need to better understand the mechanism that causes the changes in shell structure." The scientists assume it will need a series of further experiments before they can give an unambiguous description of the processes related to the mysterious islands of inversion and new magic numbers.

This work was supported by the Federal Ministry of Education and Research of Germany (BMBF) under contracts 06MT238, 06MT9156, 06KY9136I, 06DA9036I06DA9041I, by the German Research Foundation (DFG) via the Cluster of Excellence Origin and Structure of the Universe, by the European Comission within the FP6 through I3-EURONS (contract no. RII3-CT-2004- 506065), by the Fonds Wetenschappelijk Onderzoek Vlaanderen (FWO), GOA/2004/03 and IAP P6/23 (Belgium), by the Helmholtz International Center for FAIR (Facility for Antiproton and Ion Research) and the US-Department of Energy under contract number DE-AC02-05CH11231.


Story Source:

The above story is based on materials provided by Technische Universitaet Muenchen. Note: Materials may be edited for content and length.


Journal Reference:

  1. K. Wimmer, T. Kröll, R. Krücken, V. Bildstein, R. Gernhäuser, B. Bastin, N. Bree, J. Diriken, P. Van Duppen, M. Huyse, N. Patronis, P. Vermaelen, D. Voulot, J. Van de Walle, F. Wenander, L. Fraile, R. Chapman, B. Hadinia, R. Orlandi, J. Smith, R. Lutter, P. Thirolf, M. Labiche, A. Blazhev, M. Kalkühler, P. Reiter, M. Seidlitz, N. Warr, A. Macchiavelli, H. Jeppesen, E. Fiori, G. Georgiev, G. Schrieder, S. Das Gupta, G. Lo Bianco, S. Nardelli, J. Butterworth, J. Johansen, K. Riisager. Discovery of the Shape Coexisting 0^{ } State in ^{32}Mg by a Two Neutron Transfer Reaction. Physical Review Letters, 2010; 105 (25) DOI: 10.1103/PhysRevLett.105.252501

Cite This Page:

Technische Universitaet Muenchen. "Exploring an 'island of inversion,' physicists find new clues to element synthesis in supernovae." ScienceDaily. ScienceDaily, 3 February 2011. <www.sciencedaily.com/releases/2011/02/110202143800.htm>.
Technische Universitaet Muenchen. (2011, February 3). Exploring an 'island of inversion,' physicists find new clues to element synthesis in supernovae. ScienceDaily. Retrieved April 20, 2015 from www.sciencedaily.com/releases/2011/02/110202143800.htm
Technische Universitaet Muenchen. "Exploring an 'island of inversion,' physicists find new clues to element synthesis in supernovae." ScienceDaily. www.sciencedaily.com/releases/2011/02/110202143800.htm (accessed April 20, 2015).

Share This


More From ScienceDaily



More Space & Time News

Monday, April 20, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Hubble Marks 25th Birthday as Successor Readies for Launch

Hubble Marks 25th Birthday as Successor Readies for Launch

AFP (Apr. 20, 2015) — With the Hubble Space Telescope celebrating its 25th anniversary on April 24, 2015, AFPTV takes a look at Hubble&apos;s control room and gets a sneak peek inside the space center assembling the James Webb Telescope - Hubble&apos;s successor. Duration: 02:52 Video provided by AFP
Powered by NewsLook.com
Rocket Science: Building And Testing The Space Launch System

Rocket Science: Building And Testing The Space Launch System

Newsy (Apr. 19, 2015) — NASA&apos;s new rocket system will eventually be the most powerful ever built by man, but there are a lot of moving parts to test first. Video provided by Newsy
Powered by NewsLook.com
2015 NASA Rover Challenge Underway in Alabama

2015 NASA Rover Challenge Underway in Alabama

Reuters - Light News Video Online (Apr. 19, 2015) — Teams face an uphill battle for fastest rover in this year&apos;s NASA Human Exploration Rover Challenge in Alabama. Julie Noce reports. Video provided by Reuters
Powered by NewsLook.com
International Space Station Captures SpaceX Dragon Spacecraft

International Space Station Captures SpaceX Dragon Spacecraft

Reuters - News Video Online (Apr. 17, 2015) — SpaceX&apos;s Dragon spacecraft reaches the International Space Station and is successfully captured by the station&apos;s robotic arm. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins