pv2b - Slashdot User

Submission + - YouTube bans video containing Qur'an quotes

Submitted by

skraps

on Saturday February 10, 2007 @04:40AM

Father of Internet Warns Against Net Neutrality 322

Posted by ScuttleMonkey on Monday January 22, 2007 @04:54PM from the my-two-dads dept.

Submission + - Long-lived super heavy element created

Submitted by

treeves

on Wednesday December 27, 2006 @03:28PM

treeves writes: "Radioactive nuclei that hang around for a mere half-minute before falling apart hardly seem stable. Yet compared with the fleeting lifetimes of their superheavy atomic neighbors, the roughly 30-second period that transpired from creation to disintegration of four atoms of a newly discovered isotope of element 108 qualifies those atoms as rock solid.

Theoretical physicists predicted years ago that some nuclei of elements much more massive than uranium should survive for a relatively long time — possibly long enough to probe their chemical properties — if they could be synthesized. On the chart of nuclides, theoreticians pinpointed a region with coordinates corresponding to 114 protons and 184 neutrons and indicated that nuclei with those "magic" numbers of subatomic particles should lie at the center of an island of stability. The nuclear longevity, according to the models, is due to the closing of proton and neutron shells, which renders the particles stable against spontaneous fission much the same way that a filled outer electron shell endows noble gases with chemical inertness. Experimentalists, though, haven't yet found a route to reach the center of the island.

Other theoreticians calculated the effects of subshell closings in other superheavy nuclei. They concluded that an isotope of hassium containing 108 protons and 162 neutrons (270Hs) should survive a long timemuch longer than the millisecond or shorter lifetimes typical of most of the heaviest nuclides.

Now, an international team of experimentalists has detected four of those atoms and probed some of their chemical properties during the roughly 30 seconds the nuclei survive (Phys. Rev. Lett. 2006, 97, 242501). The findings confirm the predictions and provide new statistical data with which such theoretical models can be refined. The team includes 24 scientists from 10 research institutions, including the Technical University of Munich (TUM) and the Institute for Heavy-Ion Research (GSI), both in Germany, as well as institutions in Russia, the U.S., Switzerland, Japan, China, and Poland.

As TUM graduate student Jan Dvorak explains, the hassium nuclei were formed by firing a high-energy beam of 26Mg projectiles into a target enriched in 248Cm. [http://pubs.acs.org/cen/news/84/i52/8452hassium.h tml]"