ATHENA antimatter laboratory. Technician working on the ATHENA experiment at CERN, Geneva, Switzerland. ATHENA is designed to create antihydrogen, the antimatter form of hydrogen. Normal hydrogen comprises a negative electron orbiting a positive proton. Antihydrogen comprises a positron (antimatter electron) and a negative antiproton. Antihydrogen is made by combining antiprotons and positrons. The antiprotons are slowed in the Antiproton Decelerator (AD), which allows the resulting antihydrogen atoms to be studied. Any differences found between hydrogen and antihydrogen could explain why the universe is made of matter rather than antimatter.