ALPHA takes measurement of antihydrogen atoms
The ALPHA collaboration at CERN has undertaken the first measurements of the antihydrogen spectrum, reported the journal Nature last week. This initial development may pave the way towards a better understanding of why our universe is matter-based.
“We’ve demonstrated that we can probe the internal structure of the antihydrogen atom,” said ALPHA collaboration spokesman, Jeffrey Hangst. “…we’re very excited about that. We now know that it’s possible to design experiments to make detailed measurements of antiatoms.”
Scientists believe that, following the Big Bang, matter and antimatter were present in equal amounts. With the universe now predominantly made up of regular matter, the question of why the antimatter seems to have gone – and why matter has prevailed – remains one of the largest mysteries within particle physics.
These measurements of antihydrogen atoms are an important step on the path to being able to make in-depth comparisons between ordinary hydrogen and its antimatter counterpart: which may help to unravel nature’s preference for ordinary matter.
Animation of the ALPHA experiment in operation. Credit: CERN
The ALPHA experiment uses magnetic fields to trap antihydrogen atoms. Microwaves – of a specifically tuned frequency – are shone onto these atoms, flipping their magnetic orientation, and freeing them from the trap.
When these freed antimatter atoms subsequently meet ordinary matter, they annihilate, leaving behind a characteristic footprint which is picked up by surrounding particle detectors.
The ultimate aim of the ALPHA experiment is to compare the hydrogen spectrum with its antimatter counterpart. The future will see refinement of the precision of the current microwave measurements, and complementary measurements of the antihydrogen spectrum with lasers.
“Hydrogen is the most abundant element in the universe and we understand its structure extremely well,” said Hangst. “Now we can finally begin to coax the truth out of antihydrogen. Are they different? We can confidently say that time will tell.”
The paper, “Resonant quantum transitions in trapped antihydrogen atoms”1, can be found on the Nature website.
- doi:10.1038/nature10942 [↩]
