Antimatter hangs around at CERN

Scientists at CERN have published the results of experiments in which they captured anti-hydrogen particles for 1,000 seconds before annihilation.

Their work, published in Nature Physics, should yield a better basis for comparing the behaviour of ordinary matter with antimatter. The scientists say the lifetime of the particles represents an improvement by four orders of magnitude over previous work.

As Scientific American explains here, the long-life anti-hydrogen particles survive long enough to reach a low-energy state, making them more amenable to comparison with ordinary hydrogen.

Since anti-matter particles are created in high-energy environments, they come into existence in a fragile, high energy state. This poses the problem of how to trap them for long enough to lose that energy, without having the antimatter atom interact with ordinary matter, which results in the annihilation of both particles.

Charged particles can be trapped in electrical fields, but anti-hydrogen doesn’t fall into that category: with one anti-proton orbited by one positron, it has no charge. Instead, the ALPHA antimatter experiment at CERN trapped the antimatter atoms using superconducting magnets.

A comparison of hydrogen and anti-hydrogen atoms would, the researchers hope, offer up insights into the differences between the two. This, in turn, would help us understand how come our universe is asymmetrical, home to vastly more matter than anti-matter.

One goal of future work will be to scale up the successful trapping of antimatter. According to Scientific American, only seven anti-hydrogen atoms were detected and trapped in 16 experiments which created thousands of particles. ®