Study reveals the theory behind ALPHA antihydrogen breakthrough


ALPHA antihydrogen

Researchers enabled recent experiments to make the first measurement of the 1S – 2S atomic state transition in antihydrogen.

In the paper, a theoretical approach developed for the ALPHA experiment provides the insight needed to make high precision spectroscopic measurements of the transition energy between the 1S and 2S energy levels.

As a result, successful measurements made to a precision of better than one part in a billion.

According to lead author Dr Chris Rasmussen, the calculations presented here enabled the first observation of the 1S-2S transition in antihydrogen by the ALPHA collaboration, which has been a long sought goal of the antimatter community.

Researchers also points the way forward to even higher precision measurements of the properties of antihydrogen.


The physical arrangement for the experiments highly complex, and only a handful of antiatoms can trap at a time typically fewer than 20. This means careful consideration needs to given to the conditions of any measurement, to ensure the desired high precision can reach.

The authors performed a series of calculations and simulations to determine a viable experimental method for precision measurements, considering both the details of the apparatus and the low number of antiatoms available for the experiment.

Antihydrogen research underway for many years, but it is only recently that neutral antihydrogen able to trap for use in spectroscopy. One of the ultimate goals of this research is to make high precision tests of CPT invariance by comparing the energy level structure of antihydrogen.

This then becomes a strict test of our understanding of how the universe came to be in its current state, as well as of the fundamental rules governing nature. Current data for hydrogen reaches and accuracy of a few parts in 10-15, and future antihydrogen measurements aim to match this.

More information: [IOP science]