The researchers experimented with antihydrogen, which is the simplest atom of antimatter, just as hydrogen is the simplest atom of regular matter. Antihydrogen atoms each consist of one antiproton and one positron.
Creating enough antimatter for researchers to examine has proven highly challenging. To create antihydrogen atoms, the researchers mixed clouds of about 90,000 antiprotons with clouds of about 1.6 million positrons (or antielectrons), yielding about 25,000 antihydrogen atoms per attempt using the ALPHA-2 apparatus, which is an antimatter generation and trapping system, at the European Organization for Nuclear Research (CERN) in Switzerland.
RELATED: Our Universe: It's the 'Simplest' Thing We Know
After the researchers create the antihydrogen atoms, "you have to hold on to them, and that's very difficult," Hangst told Live Science. Antihydrogen is electrically neutral, which means that it cannot be held in place using electric fields, "and you have to keep it away from matter, so it has to be kept in high vacuum," he said. In addition, antimatter is best kept at temperatures close to absolute zero (minus 459.67 degrees Fahrenheit, or minus 273.15 degrees Celsius), so it is slow-moving and easier to hold on to than antihydrogen atoms.