Most contemporary scientists would argue that matter and antimatter behave roughly in the same ways, however proving it is some kind of a challenge. Why? Well, mostly because there is hardly any antimatter in the universe today. Creating antimatter particles is relatively easy in our particle accelerators, capturing and studying them, on the other hand, is extremely difficult, as matter annihilates antimatter, leaving only energy behind.

The ATRAP Collaboration, consisting of several international institutions, among which Harvard University, Forschungszentrum Julich, Johannes Gutenberg-Universitat and York University, proposes to begin the work into studying the properties of antimatter with the help of very cold atoms. By doing so ATRAP succeeded lately to create hydrogen's antimatter equivalent, antihydrogen, and captured it into a magnetic field for study.

"Our most basic theories predict that antimatter should behave like matter," says Gerald Gabrielse from Harvad University. "This is exciting, because many said that it wasn't possible to produce antimatter in the environment that we did." Gabrielse's team proved that antihydrogen can be created into a region of space where the magnetic fields experience a minimum.

Creating antihydrogen

According to ATRAP scientists, the creation of antihydrogen begins with the creation of an antiproton particle, which is then slowed by bringing it to a temperature close to four degrees above absolute zero. Then positron particles are created and also slowed down. The two antimatter particles are then forced into a collision, to create an antihydrogen atom. "If we do it at a low enough energy, there is a probability that they will get attached and form an antihydrogen atom," said Gabrielse.

There is a small problem though. Although it is antimatter and is believed that it should behave slightly differently than matter, antihydrogen, similarly to hydrogen, does not experience electrical charge, meaning it cannot be captured in an electrical field. However, by using a Penning ion trap inside a Ioffe ion trap the ATRAP team succeeded to capture the antimatter particle in a minimum magnetic field. Because antihydrogen atoms are cooled at extremely low temperatures, they have just the right quantum state which will keep them in place while inside a low magnetic field.

Although the method is ackonwledged to work, Gabrielse recognizes that it is unknown whether any antihydrogen atom has been captured yet. Their main goal was to demonstrate that the method is viable and the ANTRAP team is now working towards creating even cooler antiprotons and positrons so that the antihydrogen creation process achieves higher efficiency.

Higher antihydrogen creation efficiency immediately translates into greater quantities of produced antimatter, thus once this is done, the researching team could immediately start studying the differences between hydrogen and antihydrogen. "If we discover they have different properties, it will have huge implications at a fundamental level. If we find that they are the same, that reality does conform to theory, it's still a winning situation," adds Gabrielse.