* Astronomy

Public Lecture - Our Lopsided Universe: The Matter with Anti-Matter

NIST Physicists Chip Away at Mystery of Antimatter Imbalance

Why there is stuff in the universe - more properly, why there is an imbalance between matter and antimatter - is one of the long-standing mysteries of cosmology. A team of researchers working at the National Institute of Standards and Technology (NIST) has just concluded a 10-year-long study of the fate of neutrons in an attempt to resolve the question, the most sensitive such measurement ever made. The universe, they concede, has managed to keep its secret for the time being, but they've succeeded in significantly narrowing the number of possible answers.
Though the word itself evokes science fiction, antimatter is an ordinary - if highly uncommon - material that cosmologists believe once made up almost exactly half of the substance of the universe. When particles and their antiparticles come into contact, they instantly annihilate one another in a flash of light. Billions of years ago, most of the matter and all of the antimatter vanished in this fashion, leaving behind a tiny bit of matter awash in cosmic energy. What we see around us today, from stars to rocks to living things, is made up of that excess matter, which survived because a bit more of it existed.
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CERN experiment weighs antimatter with unprecedented accuracy

In a paper published today in the journal Nature, the Japanese-European ASACUSA experiment at CERN reported a new measurement of the antiproton's mass accurate to about one part in a billion. Precision measurements of the antiproton mass provide an important way to investigate nature's apparent preference for matter over antimatter.
To make these measurements antiprotons are first trapped inside helium atoms, where they can be 'tickled' with a laser beam. The laser frequency is then tuned until it causes the antiprotons to make a quantum jump within the atoms, and from this frequency the antiproton mass can be calculated.  However, an important source of imprecision comes from the fact that the atoms jiggle around, so that those moving towards and away from the beam experience slightly different frequencies.  A similar effect is what causes the siren of an approaching ambulance to apparently change pitch as it passes you in the street. In their previous measurement in 2006, the ASACUSA team used just one laser beam, and the achievable accuracy was dominated by this effect. This time they used two beams moving in opposite directions, with the result that the jiggle for the two beams partly cancelled out, resulting in a four times better accuracy.
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ALPHA Stores Antimatter Atoms Over a Quarter of an Hour - and Still Counting

The ALPHA Collaboration, an international team of scientists working at CERN in Geneva, Switzerland, has reported storing a total of 309 atoms of antihydrogen, some for up to 1,000 seconds (almost 17 minutes), with an indication of much longer storage time as well.
ALPHA announced in November, 2010, that they had succeeded in storing antimatter atoms for the first time ever, having captured 38 atoms of antihydrogen and storing each for a sixth of a second. In the weeks following, ALPHA continued to collect anti-atoms and hold them for longer and longer times.
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