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Author Topic: What is antimatter?  (Read 1210 times)

Ng Jing Kiat

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What is antimatter?
« on: 20/01/2011 06:30:07 »
Ng Jing Kiat asked the Naked Scientists:
What is antimatter?

What do you think?
« Last Edit: 20/01/2011 06:30:07 by _system »


Offline CliffordK

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What is antimatter?
« Reply #1 on: 20/01/2011 11:08:41 »
All "normal" matter is made up of protons, neutrons, and electrons.
Normal particles have anti-particle equivalents, antiprotons, antineutrons, and positrons.

If you are a trekie, antimatter is what makes your trek-ship go.

If you are into nuclear imaging, a PET scan (positron emission tomography), carbon-11, nitrogen-13, oxygen-15, and fluorine-18 all undergo radioactive decay be emitting an electron, a positron, and a neutrino.  These decays can be detected and will show real-time metabolic activity.  However, FMRI can give many of the same details without the radiation.

Otherwise, for the nuclear physicist, antimatter is the matter made up of the antiparticles above.

When an antiparticle encounters normal matter, it is annihilated, and the matter is converted into energy, usually gamma rays.

All of the antiparticles (antiprotons, antineutrons, and positrons) have been created in a nuclear accelerator.  Many antihydrogen atoms have been synthesized, but are short-lived, typically less than a second.

A few Antihelium nuclei have also been synthesized. 

Recent observations indicate that electron/positron pairs may be naturally created by lightening. 

If antimatter could be synthesized, or captured in bulk, it would be the ultimate power source, especially for interstellar travel where extreme power density would be desirable.  Antimatter should be able to make larger elements, but would likely have to be found naturally occurring.  Some people postulate that there are no antimatter stars, but others are searching for the possibility of large scale ongoing matter/antimatter collisions in the universe.

The Naked Scientists Forum

What is antimatter?
« Reply #1 on: 20/01/2011 11:08:41 »


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