Daily Archives: November 18, 2010

Antimatter trapped at CERN

The Daily Telegraph has a story today with the headline

Antimatter captured by CERN scientists in dramatic physics breakthrough

accompanied by the picture below and the usual razzmatrazz of antimatter-powered spaceships, antimatter bombs, Angels and Demons etc.

I first came across this strange story on Facebook early this morning and the Daily Telegraph headline iis equally puzzling. As every schoolgirl knows, antimatter is an exotic form of matter made up of particles of opposite electric charge to that of everyday matter (see post on this here). What is puzzling about the story is that physicists have been producing antiparticles in high-energy accelerator experiments since the 1950s and have been able to manufacture whole atoms of antimatter for over a decade now. (Atoms of anti-hydrogen are manufactured in accelerators by allowing anti-protons to capture anti-electons, see here).

About a third of the way down the article in the Telegraph, one discovers the real nature of the breakthrough -  the ALPHA experiment at CERN have reported that they have managed to produce atoms of anti-hydrogen that are relatively longlived (see paper in Nature here). Up to now anti-atoms were extremely shortlived because antimatter is instantly annihilated when it encounters matter (e.g. the container walls). What the Alpha group has done is to trap anti-hydrogen atoms in complex magnetic fields for up to a tenth of a second. Hence the word ‘capture‘ in media headlines, I guess.  It is certainly an important breakthrough as it should enable a detailed study of subtle differences between atoms of hydrogen and anti-hydrogen. (For example, in what way does the spectrum of anti-hydrogen differ from that of ordinary hydrogen?)

The Alpha experiment – don’t try this at home

This is an important area of study because any differences in the spectrum of anti-hydrogen vs ordinary hydrogen could shed light on one of the greatest mysteries of particle physics and cosmology; why is our universe made of matter? What subtle imbalance occurred in the early universe that led to the survival of ordinary matter over antimatter? From the point of view of particle physics, it wll be very interesting to see if CPT symmetry is conserved in the case of anti-hydrogen: if not this has implications for the standard model of particle physics.

Almost everybody in the particle physics universe is blogging on this breakthrough today so I won’t comment further – there is an excellent summary of the experiment on the Symmetry Breaking blog

Update

Kate McAlpine (author of the great LHC rap) has an excellent article on the above in this week’s edition of New Scientist . It’s well worth a look, especially her explanation of how neutral anti-atoms can be trapped in a magnetic field.

Update II

When the film Angels and Demons came out, Dan Brown was widely criticized for suggesting that enough antimatter could be trapped long enough to form a stable bomb (see post and review of A&D here). Looks like Brown wasn’t quite so far off the mark after all – at least about entrapment, if not about a feasible amount of antimatter for a bomb. My guess is that he had some serious discussions with the CERN group, just as he claimed at the time..

Not quite so daft

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Filed under CERN, Cosmology (general), Particle physics