Antihelium Discovered By STAR

Posted by Soulskill on Monday April 25, 2011 @05:54AM from the makes-your-voice-really-low-then-vaporizes-your-lungs dept.

Medevilae writes with this excerpt from ScienceBlog: "Eighteen examples of the heaviest antiparticle ever found, the nucleus of antihelium-4, have been made in the STAR experiment at RHIC, the Relativistic Heavy Ion Collider at the US Department of Energy's Brookhaven National Laboratory. ... Ordinary nuclei of helium atoms consist of two protons and two neutrons. Called alpha particles when emitted in radioactive decays, they were found in this form by Ernest Rutherford well over a century ago. The nucleus of antihelium-4 (the anti-alpha) contains two antiprotons bound with two antineutrons. ... 'It’s likely that antihelium will be the heaviest antiparticle seen in an accelerator for some time to come,' says STAR Collaboration member Xiangming Sun of Berkeley Lab’s NSD. 'After antihelium the next stable antimatter nucleus would be antilithium, and the production rate for antilithium in an accelerator is expected to be well over two million times less than for antihelium.'"

1 of 94 comments (clear)

Min score:

Reason:

Sort:

Re:Okay, I get some of this . . . by pclminion · 2011-04-25 06:42 · Score: 4, Informative

An anti-neutron is like a neutron, but instead of being composed of an up quark and two down quarks, it is composed of an anti-up quark and two anti-down quarks. Each of the quarks has an electrical charge -- they add in such a way that the sum is zero. For an anti-neutron, the quarks have the opposite charges as before, but they still all add to zero.